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THE CHILDREN OF GALLIFREY
The Biology of Modern Gallifreyans


"That is a reflex link, whereby I can tune myself into the Time Lord intelligentsia.
A thousand super-brains in one."
"Why don't you do it now?"
"What? Oh, well, I lost that particular faculty when they kicked me out."
- The Doctor and Leela
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TABLE OF CONTENTS

Gallifreyan X-ray

Click on paragraphs to see color coding for sources

Gallifreyan Loom Gallifreyan Cradle
A Gallifreyan Loom and Cradle for a Childe Loom
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THE LOOMING OF A GALLIFREYAN

The Curse of the Pythia rendered almost all Gallifreyans are sterile. Some Gallifreyans claim that their species is immune to being seduced with erotic temptation. Though they are physically capable of sex most have almost no sex drive. Many, like the Doctor, live most of their lives in celibacy. For these reasons, each Chapterhouse has one Genetic Loom Breeding-Engine with a unique genetic core to loom its cousins. Every Gallifreyan is born into one of Rassilon’s Great Houses and the Honorable Central Population Directory defines the quota of cousins for each House's Loom. This directory is directly controlled by the High Council. In the pre-Time War era there are between 3 and 9 million Gallifreyans living on the planet.
A loom consists of a gene-weaving frame with millions of fine cords which weave matter (probably rapid growth biomass) and biodata together in a vat of semiotic fluid.  The subject begins as an egg with the consistency of jelly. They smell of tangy celestial potental. The frames of some looms are silver. A new loom probably takes over 11 years to produce its first loomling. The Looms are held in the loomshed of the physical house. Each House's loom has its own genetic Loom core, which serves as its genius loci. Using its biodata extractor, this core creates a template that standardizes the abilities and blood of everyone loomling of that family. Members of each house have minor variations in abilities unique to their house. An experienced vampire can tell which house a Gallifreyan came from by the taste of their blood. The loom weaves a random body based on that House's basic, but unique, template. Thus there is no way for someone to control the appearance of a new childe. So while the chances of a duplicate regeneration is relatively high, the appearance of all first incarnations are unquie. The Looms produce produce male, female, and indeterminate gendered Gallifreyans. Just over 10% of loomlings are female. The Looms are complex anchors in time designed to link the Gallifreyan to Gallifrey and, by extension, the Web of Time. As such they have limited knowledge of the future of every loomling. A loom automatically record the genetic metamorphosis every time one of its cousins regenerates. They probably weave not only DNA but also give each loomling a distinct future. For several days spirals of data flow down these cords and are woven into a mesh. From this mesh a Gallifreyan Childe is formed within a tube. During this time Loom-Tenders supervise and occasionally sing traditional rhymes. Mistakes in the weft could result in deformities that even regeneration couldn't fix.
Depending on the programing that house's loom core, some looms produce offspring in the form of a small childe (physically resembling a human child), but most loomlings emerge as full grown adults. Looms that produced childrene were kept inside cradles. These childrene have milk teeth. Memetic priming was used to give the loomlings foreknowledge. A loomling will have trouble using proper grammar, but can walk right after Looming. It should be noted that Gallifreyans break most of the laws of biology before they take their first step.
Novice
A Gallifreyan Childe
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CHILDEHOOD

A Gallifreyan childe ages slower then Humans and it takes hundreds of years for them to mature into what a Gallifreyan would consider an adult. At 5 years old, loomlings are amazingly intelligent An 11 year old would look like an 8 or 9 year old human, but a 16 year old would look like an earth teenager. At around this point their aging slows dramatically - a 48 year old would look like an 18 year old human. Some suffer from acne for over 50 years. Someone around 60 would still still look like young adult but would considered to be a very young childe. Gallifreyans in their teens need as much food as a human teenager if not more. Adult Gallifreyans eat about as much as human. They are still considered kids at age 90 and a lad at 100. Young Gallifreyans need to sleep a little more then most humans, but after they pass First Maturation and learn to control their bodies, they only need 1-2 hours a day. Because they can not control their bodies teenagers have far less resistance to cold then adult Gallifreyans.
A Gallifreyan
An Adult Gallifreyan
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FIRST MATURATION

Gallifreyans are not considered legal adults until they reach their majority at 200 years old. This is probably the age at which First Maturation occurs. 750 -850 years old is considered to be analogous to "approaching middle age." Many complain that their bodies become more physically limited (in strength and stamina) right after they turn 950. Subsequent Maturations probably refer to the life-span of each regeneration.
Exposed Time Lord Biodata Biodata Extract Biodata Extract
Exposed Time Lord Bio-Data and Bio-Data Extracts
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MODERN GALLIFREYAN GENETICS AND BIODATA

Gallifreyans have Triple Helix (aka tri-strand) DNA as well as TNA. The extra third strand was added by Rassilon to make Regeneration possible. Hidden in Gallifreyan DNA are 'killing lessons' to destroy Cacophony should she ever reappear. To make sure Gallifrey can never be threatened by the Spore again, there is an inherent immunity to them created by a few lines of resistant structural code in the genome of all Gallifreyans. This immunity is based on the Spore’s self-destruct toxin. The DNA of every previous incarnation lies dormant inside a Gallifreyan's body. By the time he had regenerated 7 times the Doctor (and presumably other Gallifreyans) have 69 chromosomes divided into 23 homogeneous triads. Time Lords share 98% of their genes with Vampires. They are vulnerable to some earth viruses, like influenza, fevers, pneumonia, and the common cold. They can also suffer from rheumatism and catabolisms. If a Gallifreyan develops an immunity to a virus that immunity will persist in each new incarnation. They have developed a single Gallifreyan restorative that cures 90% of all plagues and ailments capable of affecting a Gallifreyan. Before the curse fades almost all Gallifreyans are sterile.
A person's Biographic Data (usual called bio-data) is the sum total of the 4 dimensional space that their life forms in space-time - everything they are, have done, or will done is part of a sapient being's bio-data. Altering bio-data can change a person's nature, or their past, or their future. Every Gallifreyan has an Bio-Data Extract (aka biog-data extract, or D-E, or artron imprint) sample removed and compressed with an artron energy codifier. This sample is stored by Coordinator of the Matrix and viewable only by the Coordinator, the Castellan, and members of the High Council. Losing one's virginity makes it much more difficult (if not impossible) for Gallifreyan technology to read ancestral memories from the subjects biodata. Transmission of an extract is considered treason. There are millions of Time Lord extracts stored in the Archival Office (implying that Gallifrey has had more then 1000 Time Lords alive at any given time for much of it history), but as of The Ancestor Cell a total of only 153,846 Time Lord minds have been uploaded into the Matrix. Extracts of Time Lords are color coded by chapter. Time Lord D-Es can only be accessed by the High Council or the Castellan and all accesses are logged.
Time Lords can use a transfer of bodily fluids [say through a kiss] to make a genetic transfer to another species.  This other species will then carry the biometrical signature of the Time Lord. Depending on how it done the effect can last for less the a few weeks or for years.  This might be achieved by altering the subject's morphic fields.   
Gallifreyan Brain Gallifreyan Brain
The exterior and interior of a Gallifreyan's Brain.
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GALLIFREYAN BRAIN

Gallifreyan brains are green in color and larger then a human's. The brain is divided into two hemispheres. One side is the seat of reason, known as the brain proper. The other is the seat of imagination, know as the mind. There is an interface connecting these two hemispheres, and at that point things can exist purely as concepts without corporeal form. Under some circumstances, a Gallifreyan brain will actually light up when the Gallifreyan speaks (though this effect is concealed by the skull).
They have Super-ganglion which allows them to re-order, re-rout and re-program their neural pathways at will. Among other things this bio-rhythmic control allows them to separate the operation of the two hemispheres of their brains, greatly boosting their ability to multi-task. They can bypass compromised areas of their brains and switch off the parts of their brain that process input from various senses, allowing them to limit their vast number of senses to the same range as a human. Through an act of will, a Gallifreyan can compartmentalize pain to the degree that they can block the pain from a severed limb. This makes them immune to some types of interrogation technology. They have the ability to shut down the right or left side of their body. They can lower their need for oxygen, and even control their heart beats to send messages. They can also use this versatilely to destroy crystalline structures that might invade their nervous system. One of the side effects of this is that 21st century Cybermen are incapable on cyber-converting a Gallifreyan. Depending on how their brain is currently configured it can throw their biorhythms 'off', and in such a state it can sometimes take them a while to notice the blindingly obvious. Having their second heart removed prevents them from reprogramming how their eyes work (and possibly other alterations as well).
A Gallifreyan’s hind-brain is the center of the survival instincts. It can flood the panic centers of the mind with amines and corticals to induce anxiety. The Epiphysis Cerebri‎‎ on a Gallifreyan is twice the size of a humans. It is sometimes known as the Third Eye and is the part of the brain that is the source of psychic activity. A dormant throwback organ in their brains can allow them to sense higher dimensions (with training). Their brains also have a Lateral Interpositus Nucleus. At the base of their brains is a separate tertiary lobe called the Autonomic Brain that handles all body and motor functions. This gives them a total of 3 brain stems. A Gallifreyan’s autonomic brain is like a helper mind that can be told to do and monitor simple things while the main consciousness thinks about other things. It can even send non-descriptive alerts to the mind. By voluntarily reducing the activity of this third lobe to a vegetative state, a Gallifreyan can use a nerve cluster of major ganglion to take direct control over their metabolism. This nerve cluster is located along their left collar bone beneath the left clavicle. With sustained concentration Gallifreyans can send messages to the parts of their autonomic brain that controls various systems (like the circulatory system). This allows them to consciously modulate and control the details off that system. They can double the pace of their body's functions if necessary.  Unfortunately a blow at this at this cluster will render them unconscious.
These systems frees the rest of the brain for purely intellectual pursuits, allowing them to think of at least 3007 ideas in 3 seconds and achieve mental calculations beyond that of most sapient species. There is even a case of a Gallifreyan brain being able to determine how to avoid being hit by energy beams from 50 attackers while ploting out how to use those beams to charge the device they are carrying - all in 4 nano-seconds! If these basic body function are being handled by an external life-support system then Gallifreyans are even capable of adjusting or reprogramming their autonomic brain for more complex processes, such as consciousness and communications. An electroencephalograph of a Gallifreyan brain will show a type of activity unlike any human brain. While human alpha waves are generated by the occipital lobe, Gallifreyan Alpha Waves are generated by the hypothalamus. If all other forms of communication have been disabled they can communicate via reduced-frequency alpha waves. They are much more vunerable to changing magnetic fields then most humanoids are.
Gallifreyan short-term memory is such that, if they concentrate, they can remember the smallest details of the last few minutes. They also have a greater long-term memory storage capacity than a human and can generally have perfect memory of everything they experience (consciously or unconsciously) in the last 300 years or so (in that incarnation). This perfect memory is sometimes called 'The Curse of the Gallifreyans.' Exposure to cronon particles (like those emitted by a TARDIS) can help a Gallifreyan recall memories that he hasn't accessed for several centuries. Gallifreyans can check their own minds for dead spots in there memory to tell if there’s any damage to their brain. Unfortunately, because of their artificially extended life span, Gallifreyans need to clear out some of their memories every few thousand years. They usually store the more important memories using telepathic circuits. For more extreme modifications Gallifreyan psychosurgeons are needed. Gallifreyan memory wiping techniques aren't totally reliable and the memories often reappear as dreams. Despite their genetically engineered origin, Gallifreyans have race memories, some of which relate to the Chronovores.
Gallifreyan Eye
Gallifreyan Eye
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GALLIFREYAN NERVOUS SYSTEM

Their retinas are so sophisticated that they can almost think on their own. In addition to rods and cones their eyes are equipped with octagons, gives them amazing night vision and the ability to see, and recall, an amazing amount of detail in something over 100 yards away. They can shift their vision outside the normal visual spectrum allowing them to see a total of 170 different levels of the electromagnetic spectrum, including in some shades of ultraviolet. However, having their second heart removed prevents them from reprogramming how their eyes work. Their eye color can change from brown with flecks of gold, to midnight blue to deep purple. Such changes appear to depend on their mood. The eyes of the Older House are flecked with purple. Their pupil response is very different from humans and can resist super intense photo-emissions that would permanently blind a human. They can control the musculature of their eyes to bring things into a very precise focus. (If they remember to check) they can tell whether a humanoid is Gallifreyan just by looking at them. Despite all this, blindness is not unknown on Gallifrey. Gallifreyans can erect non-porous barriers around their noses, ears and eyeballs that prevent any intrusion on the molecular level. They appear to blink a lot less often the Humans. Despite this, an unprotected Gallifreyan's eyes will be permanently destroyed if exposed to the cold and vacuum of space for too many minutes.
A regenerated Gallifreyan's, hearing and smell is better than human's. Some Gallifreyans can perform biochemical analysis of what they taste including identifying blood type. They can use their sense of smell to perform chemical analysis of the air. And, unconscious Gallifreyans can often be awakened (even from a healing trance) with a heated infusion of free radicals, antioxidants, and tannin (aka boiling tea vapor). The scent of Celery is considered to be another powerful restorative on Gallifrey. A Gallifreyan can hear significantly higher frequencies then a human. Many Gallifreyans are capable of amazing voice imitation. Thus locks with voice prints are not in common use. Compared to humans, Gallifreyans are quite resistance to dizziness and other inner-ear disorientation caused by sudden changes in position. They also appear to have increased resistance to high frequency sonic attacks. 
Gallifreyan Breath
Breathing Gallifreyan
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GALLIFREYAN RESPIRATORY SYSTEM

Gallifreyan lungs are made up a of a series of pulmonary tubes that run parallel to the lymphatic network. These tubes can absorb every single molecule of oxygen inhaled and exhale the carbon dioxide. Thus, they need less (only 1/4th as much) oxygen as a human to function normally and normally take only 4 breaths a minute. Despite this, Gallifreyans in older bodies could be affected by altitude sickness. The presence of extensive moisture during a regeneration can cause a Gallifreyans to have some trouble breathing in humid environments in their new incarnation. The unique structure of their advanced respiratory system keeps them buoyant in water, making swimming easier.
Gallifreyans have a bypass respiratory system and a secondary cardiovascular system. When properly trained, this system lets a Gallifreyan survive in almost any atmosphere where some oxygen is present. When consciously triggered, the bypass system contracts, closing off their primary respiratory passages making them very resistant to most forms of anesthetic, ether, cyanide, strangulation, hanging, and the squeaky voice caused by helium. Gallifreyans are also much more resistant to mercury poisoning than Humans. Mustard Gas is still deadly however. But they must remain completely calm. Any pain or unexpected shock will can cause them to exhale the air in their lungs. The bypass respiratory systems also allows them to hold their breath for several minutes and, with warning, a Gallifrey can store enough oxygen in their system to be active for 20 minutes. If this is insufficient they can enter self-induced sleep trance in which breathing, heart beat, and brain activity are all reduced to an absolute minimum. In this state they can hold their breath for hours, but they will appear dead to most humanoids. The bypass respiratory system allows them to remain conscious in hard vacuum for 3 minutes and survive, in an unconcious state, for over 30 minutes. It might even allow a Gallifreyan to function underwater. They lose their sense of smell when they rely on their Bypass respiratory system. Gallifreyan's with only one heart will not be able to use their bypass respiratory system. As Gallifreyans pass 1000 years of age their bypass respiratory system becomes less reliable and there is a chance that they won't be able to awaken from its use.
Gallifreyan Hearts Gallifreyan Hearts
Twin Hearts of a Gallifreyan
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GALLIFREYAN CIRCULATORY SYSTEM

Most Gallifreyans are loomed with one heart. When they regenerate for the first time they acquire a second heart that is a mirror image of the first. Newblood Gallifreyans are loomed with two hearts, making them bicardial from the begining. A Gallifreyan’s second heart helps with their fast healing (limbic gland?), allows them to go without sleep, gives them greater strength and endurance, and resist temporal shocks. It is part of the respiratory bypass system. Without this heart they will get chilled much more easily. Their hearts are bivalved and each heart beats at a different rate, producing two distinct beats per cycle. While recognizably a heart the exterior shape and structure of a Gallifreyan heart is very different then a human heart. After regeneration, most Gallifreyans have two hearts (a primary and a secondary) each of which usually beat 60 times per minute and normally fibrillate at a rate of 300. A double pulse of 170 (85 per heart?) is considered more or less normal. The beats are quite powerful making it difficult for the hearts to be exactly located with a stethoscope. The electrical activity of the hearts is much greater then a humans and Gallifreyan have been know to survive lightning strikes and shrug off a shock of 430 Volts. However human physicians have theorized that the monotony of the occurance of inter-caval conduction block during atrial flutter would mean that the anatomy or electrophysiology of Gallifreyan hearts give them a predisposition for conduction abnormalities.
Both hearts are supported by a binary vascular system. This binary vascular system gives them voluntary control of their heart-rate. They can make their hearts work in overdrive. Though this is quite painful it provides vast reserves of stamina. As childrene, Gallifreyans are trained to stop both their hearts and feign death for several hours. Some can even alter their metabolism to the point where they will appear dead to medical sensors from a level 9 society. But once a Gallifreyan stops spending his life functions and returns to full life they can not re-enter this state of suspended animation for some time. They can voluntarily dilate and contract their control blood vessels.
They can survive with only 1 heart beating, and can often restart the other by pounding on their own chest. In cases of a single heart attack, a Gallifreyan will be greatly weakened. To be effective CPR must be performed on both hearts (which is why Gallifreyan Cardiovascular Stimulators always come in pairs). Gallifreyans have been known to withstand up to 35 atmosphere's of pressure, but this usually causes at least one heart to fail. Massive blood loss can trigger a double heart attack. The removal of one heart results in the temporary loss of many Gallifreyan and Time Lord traits while a new heart is grown. The hearts are linked, and if someone has a Gallifreyan heart transplanted into their body they will be linked to the donor Gallifreyan and it will be very difficult to kill the donor without killing the receiver as well.
A Gallifreyan's blood pressure is normally much higher then a humans, but can drop to 70/70 millimeters of mercury when recovering from a regeneration. Gallifreyan blood is darker than human blood and reddish-orange. It doesn't conform with any form of human blood because it has a different pathological state and lots of acids, not found in humans. These acids perform various functions including the self-regenerating genetic imprimature of the biogenic molecules. These molecules clean out their arteries to prevent them from becoming clogged. The respiratory pigment doesn't use hemoglobin but does share some of structural characteristics of human hemoglobin. Their blood carries a unique artron energy signatures and the temporal platelets cluster around any wound, accelerating time in that area to speed the healing. These advanced platelets detect even tiny amounts of toxins. Their immune system resists disease more effectively so they are rarely suffer severe illness. There are however a few diseases that can incapacitate Time Lords without affecting humans at all. 
In human terms, their blood doesn't have a type, however there is a Gallifreyan classification system. All the cousins of a single house will have the same blood type.  Within this system, TL Positive is the rarest type. Successful transfusions between Gallifreyans with different blood types is not possible due to differences in their extra-cellular matrix. Due to its regenerative properties, Gallifreyan blood is in a constant state of genetic flux. Not unsurprisingly, it doesn't smell like human blood. However, because of its unique nature it can be transfused into any human without complications. Due to their transcendental circulatory system, a Time Lord can donate much more blood then could be contained in a human body of the same size.
Time Lords can use a transfer of bodily fluids to make a genetic transfer to another species. Their anti-bodies are symbiotic so if a Gallifreyan is injected with a sample of genetically contaminated blood their immune systems can create anti-bodies of such sophistication that when injected back into the original donor they ‘teach’ the victim’s white corpuscles how to break down the hostile DNA. This other species will then carry the biometrical signature of the Time Lord. A human recipient will feel rather energized, probably because it carries oxygen (and other gases) vastly better than human blood. Depending on how it done the effect can last for less the a few weeks or for years.
Artron Energy
A Gallifreyan surounded by Artron Energy
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GALLIFREYAN PSIONICS

It took several generations of genetic engineering to re-introduce psychic abilities to the loom born Gallifreyans, but in the modern era, all Gallifreyans are psychic.  Though some have greater psionic sensitivity then others, most are low level telepaths. The Epiphysis Cerebri (pineal gland)‎‎ on a Gallifreyan is twice the size of a humans. It is sometimes known as the Third Eye and is the part of the brain that is the source of psychic activity. Gallifreyan psionics work via neural congruence and sympathetic resonance. Gallifreyans suffer psychic feedback, fever and headaches as their telepathic abilities mature. Whenever two Gallifreyans meet there is a courtesy mind-touch to identify and acknowledge each other. Every Gallifreyan has a unique psycho-kinetic signature.  This allows them to recognize each other even if they are wearing a new body. Their telepathic intuition allows them to determine which people are Gallifreyans and which are not.
A more prolonged telepathic contact between two Gallifreyans occurs when they form a Psychic Bridge. To initiate this contact one must use an almost impossibly narrow band frequency. This telepathy generally worked better if eye contact could be made - though some Time Lords preferred head-butting the other person. It’s easier for a Gallifreyan to make contact with another Gallifreyan then it is to contact the minds of other species. They are also able to tell if humans are telepathic or not. They can read the last few moments of life from the artron imprint on a recently dead skull. 
Gallifreyans can use touch telepathy to form entrelacement. This is traditionally done by having one Gallifreyan touch the other's face and both announcing 'Contact.' Entrelacement allows the mutual transfer of emotions and large amounts of information very quickly. Entrelacement is generally reserved for people with a very intimate relationship. 

Its even easier for a Gallifreyan to contact another version of themselves (especially if they are in the same time zone). If they are trying to telepathically contact one of their own incarnations they don't even need to be touching. Indeed such contact can be made via the astral (the 5th Dimension) plane over galactic distances and times. Psychic pulses travel at a 170,000 times the speed of light. Time Lords attempting to send telepathic signals through the Astral Vortex can encode them with their own psychic patterns. This makes it impossible for anyone to decode the message except a future or past version of the transmitting Time Lord. Care should be taken as interruption while accessing the Astral Plane can leave the Gallifrey's mind trapped in the Vortex, thus killing his body. The artron energy of the Astral Vortex can charm and enchant even a Time Lord's mind to the point where they might not have the willpower to return to the three dimensional world. Deja Vu is another form of Astral Projection.

The strong psychic empathy field which Gallifreyans have allows them to hypnotize others. Eye contact appears to be nessecary for this to happen (probably because artron energy is the energy of perception itself). Some of them can telepathically block or scramble a person's memories back to an arbitrary point in their life. They can even implant post-hypnotic suggestions in people who are trying to read their minds.

Artron echos are emited by all sapient beings. The greater affect that a person is going to have on coming history the stronger the echos. Residul psionic energy makes a Gallifreyan’s teeth itch. The older the energy, the stronger the itch. Every Time Lord possesses an entire quantum of Artron Energy which gives them a unique artron energy signature. Time Lords tend to accumulate more artron energy as they travel the Vortex.  To prevent it from reaching dangerous levels, the amount possesed is reset with each regeneration. Gallifreyans generate Artron Energy traces that can be used by others to determine their age and identity. This is significantly more life-energy than a human has. This is because Artron Energy levels are determined in part by the subjects total life-span (past and future). It's possible that Gallifreyan females might be more gifted with telepathic abilities. The energy they possess increases by a minute amount every time they pass through the Vortex. The Matrix also enhances the Time Lord telepathic powers.

They are capable of absorbing lethal amounts of artron energy from another humanoid. After doing so a regeneration will be necessary to eliminate the energy. Experienced time travelers have high enough artron levels that they can also donate some of their energy to assist another Gallifreyan in a regeneration or even to recharge a TARDIS Power Cell (but doing so consumes 10 years of their total lifespan).
Some Gallifreyans can temporarily swap psychic mind-scents with someone else for a short period. When this is done others will perceive the two as having swapped appearances. This will cause any psychic hunter to follow the wrong target. The mineral Asomidium (found in an asteroid belt in the Kasterborous Sector) was used to enhance Gallifreyan telepathy and was like an essential component in Gallifreyan Neural Amplifiers which boost such abilities. The legendary Resonance Engine, whose plans are hidden in the Matrix is the most powerful of such devices. Gallifreyans can uses a process called Soul Catching to absorb a dying Gallifreyan's memories.
Gallifreyan Skull
Gallifreyan Skull
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GENERAL GALLIFREYAN BIOLOGY

Gallifreyans are bipedal. Aside from two extra ribs (for a total of 26) a Gallifreyan's skeleton is almost identical to a humans. Their teeth are immune to normal forms of tooth decay, so they never needed to brush their teeth. However, when damaged, they can end up needing fillings inserted in their teeth. These fillings are supposed to regenerate when their body regenerates (though this process isn't perfect). By human standards, most Gallifreyans are 1.5 - 2 meters tall, with solemn, learned faces.

Gallifreyans have got multiple organs of virtually everything. They have 2 of most of the organs that humans have only one of, and 4 of the organs that humans have only two of.
Some sources say the have only one liver, others say two (this could vary from House to House?) The also have several organs that have no real analogue with those found in humans. Indeed, despite looking like humans from Sol III, biologically speaking Gallifreyans have much more in common with Chelonians. Just about every one of their organs are much more efficient and effective then a human’s equivalent. Their internal body temperature is 15 (or 16) degrees Celsius (59 to 61 degrees Fahrenheit) however their skin temperature is only a little below the human norm. With a a fair amount of concentration, a Gallifreyan bring their body temperature down to 34 degrees Fahrenheit, though their attention span is greatly reduced. By speeding up their heart rate a Gallifreyan can raise his body temperature to levels high enough to steam dry their soaking wet clothes in 20 minutes. This heat is such that it can become uncomfortable for humans who have to touch a Gallifreyan for a long period of time.
Gallifreyans tend to find a room temp of 20 C to be uncomfortably hot. Despite this, adult Gallifreyans are capable of withstanding extreme temperatures at both ends of the scales. Due to their low body temperature, spending several minutes immersed in ice filled water feels briskly refreshing to a Gallifreyan. They can withstand 200 degrees C for up to 3 minutes and remain aware and physically active in the -270 C cold of outer space for 6 minutes (though they can be permanently blinded if their eyes aren't protected). T temperatures of several hundred degrees below 0 C will cause a Gallifreyan to lose control of their body and appear dead. But even in this state their mind is infact very active. They can't experience true thoughts or memories at these temperatures, but emotions and impressions from there senses can be perceived. Freezing a Time Lord for millions of years is likely to cause temporary amnesia. Gallifreyan's with only one heart suffer chills much more easily and probably find extremely low temperatures to be significantly more painful.
 Gallifreyan probably have tonsils and its not probably not unknown for them to have to be removed. Gallifreyans have more than one stomach and are not as vulnerable to malnutrition as Humans are. Some (if not all) believe that only one meal a day is perfectly normal. Despite this their metabolism is relatively close to a humans and they can eat the same foods. They don’t have to worry about eating too much fried food due to the biogenic molecules that clean the arteries. Some Gallifreyans can use their stomachs to interpret human memory RNA and producing the Gallifreyan equivalent. They and can easily go two days without water and a week without food is not a major strain. While they sometimes sit in thought for days without food or water Gallifreyans tend to be cranky if they don’t eat regularly. There are limits, 40 days without food or water will make a Gallifreyan delirious. Gallifreyans metabolize alcohol very quickly so it is almost impossible for them to become drunk or suffer the effects of hallucinogens. Thus can easily drink 10 pints of beer without showing any ill effects. It takes roughly twice the normal amount of sedatives to knock them out. Some Gallifreyans can use special meditations to regulate their metabolism. This gives them a very fine control over the rate at which they metabolize alcohol, making inebriation or hallucinations possible. However Ginger pop has a severely deleterious effect on any Gallifreyan metabolism. This allows them to be easily effected by any alcohol they might have consumed. Detox can render psilocybin harmless by modifying its chemical structure. They need to urinate every few days.
Arsenic is toxic to Gallifreyans and will inhibit their enzymes. If a large source of protein, salt, and other chemicals (found in ginger beer) are available a Gallifreyan who has been poisoned with arsenic can use a major shock or surprise to trigger Detox. This detoxification allows their stomach to stimulate inhibited enzymes to reverse and release all toxins a gas that can be exhaled. Aspirin is incredibly toxic to Gallifreyans. When exposed, an allergic reactions occurs when aspirin begins to interfere with hormone receptor intermediaries,stops platelet aggregation, and interferes with a Gallifreyan's genetic structure. All of this causes a massive pulmonary and cerebral embolism, severe enough to prevent regeneration. Even touching Aspirin can be dangerous. Detox can be used to negate aspirin poisoning if the Gallifreyan can consume some chocolate. The simple triglycerides in the chocolate combats the anti-platelets effect of the aspirin. The Detox procedure doesn't work for all toxins. While aspirin (and many other human medicines) is toxic to a Gallifreyan metabolism, they can handle 20th century broad spectrum antibiotics without significant trouble.
Adrenalin significantly improves a Gallifreyan’s coordination. They have endorphins that are produced up when they are feeling exhilarated, but are not released while exercising (unlike in Humans). Kicking their two hearts and bi-vascular system into overdrive lets their whole body run at double a human's rates. This causes them pain and some dizziness – but gives them vast reservoirs of stamina. Gallifreyans don't have prostate glands. When trained they can control their adrenaline, blood-sugar levels, heart rate, respiration, and perspiration to the point where they can fool 23rd century medical diagnostics into thinking they are human. They can even switch off any of their organs at will.

They also have control over the speed and location of their hair growth. They can grow hair faster then humans or stop the growth completely. Despite this
some Gallifreyans still shave their faces. TThe most common hair colors are black, brown, blond, and white.
While a Gallifreyan's skin often smells like honey, they can easily change their scent at will using olfactory misdirection. This allows them to hide from predators that hunt by scent. They have a wide range of smells they can pick from. Their skin has extra subdural and subcutaneous layers that will eject foreign objects such as subcutaneous implants. In order to keep an implant inside a Gallifreyan it must be attached to the cartilage. All of this makes their skin very resistant to radiation, physical damage, poison ivy, sunburns, and tanning. Gallifreyans can resist radiation that will kill a human in 4 minutes for 2-12 minutes before they start to take noticeable damage, and they are completely immune to some types of radiation. They can easily absorb 50 times the output of a 21st century medical X-ray machine (approximately 50 rems of Roentgen (aka X-Ray) radiation) and them expel it into any object they they can touch. A radiation level of Q15241 is not dangerous to a Time Lord. And a level of Q34911 is only safe for a short period. A major exposure to radiation (approximately 2,000 rems for 1 hour) will take 23 days in a healing trance to expel. Any higher dose will require a regeneration. Incarnations which appear to be physically younger are much more resistant to radiation then older bodies. However 500,000 rads will kill even a Time Lord within a few hours.
Gallifreyans can erect non-porous barriers around their noses, ears and eyeballs that prevent any intrusion on the molecular level. Combined with the enhanced skin, a Gallifreyan can easily survive twice as long as a a human can in most hostile environments. With an oxygen supply this allows them to remain conscious for 6 minutes and survive up to 20 minutes in space unprotected. Without an oxygen supply they will only have 3 minutes of consciousness. Despite the above mentioned barriers, an unprotected Gallifreyan's eyes will be permanently destroyed if exposed to the cold and vacuum of space for too many minutes. Most humans are stronger then the average Gallifreyan (but, due to their second heart, and exposure to the Untempered Schism, Time Lords have incredible strength for their size) They can remain conscious when exposed to G-forces that would kill a human.
Gallifreyans need far less sleep than most humanoids. Popular concensus is that 1 hour sleep a day is more then enough. This is because a Gallifreyan can enter self-induced trance where they can ponder complex ideas without any outside distractions. 20 minutes in this state is equivalent to 8 hours of sleep for a human. Thus they only need about 1-6 hours of sleep every 2 days and they have the advantage of not requiring to take their rest in bulk. A ten minute doze here, a half hour snooze there, is a valid contribution to their three hour quota. While some become tired after only being awake for only 4 days, others have periods of hyperactivity followed by days of sleeping. While most prefer 1-3 hours of sleep a day, some Gallifreyans can even get by on a decade of sleep every 100 years. Gallifreyans might be able to sleep standing up. Gallifreyan's with only one heart will find that they need much more sleep then a two hearted Gallifreyan. Gallifreyans rarely dream, but when they do, they sometimes dream of choosing their next bodies, being able to fly, becoming the opposite sex, and bearing childrene. Because dreams can access the astral vortex, Gallifreyans who have nightmares (a very rare occurrence), or find themselves in near-death states, sometimes meet their Gods (Time, Death, Pain, etc). Often a deal or agreement is made and sometimes the Gallifreyan becomes that Eternal's Champion. Gallifreyan who have regenerated in that last few days will require a lot of sleep, even by human standards.
Biogenic Molecules Regeneration
Biogenic Molecules and a regenerating Gallifreyan
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REGENERATION - Telebiogenesis, Face-Lift

NOTE: Several sources claim that Time Lords are the only Gallifreyans who are capable of regeneration. But several other (equally valid) sources show normal (ie non-Time Lord) Gallifreyans regenerating without anyone considering it unusual. Dependiong on your point of view, one could argue that this section should be located on the Time Lord page and not the Gallifrey Biology page.

On a deserted world on the far edge of another galaxy Gallifrey's first space traveller, the Shobogan Tecteun, discovered a gateway to another dimension or universe. Near this gate she found a male child (later known as the Doctor) who had been thrown through the gateway and abandoned. This child was capable of regenerating their entire body whenever they were on the point of death and became known as the Timeless Child. Like the Untempered Schism, the gateway might have surounded the Child's body with bio-plasmic fields of regenerative cronon energy. Tectaun realized that the Child's abilities were connected to the immortal, self-regenerating nature of the Universe. Studying the defiance of the thermodynamics of this phenomenon eventually led Tecteun to devise a way to splice into herself the ability to regenerate. In order to extend the already long Gallifreyan lifespan, the Shobogan leadership of Gallifrey decided that future generations of Gallifreyans living in the Citadel would benefit from the gift of regeneration (sometimes known as the Legacy of Rassilon). The Timeless Child appeared to have timeless, perpetual, bodily regeneration (however he once claimed he could only regenerate 507 times). Tecteun chose to limit the number of regenerations for this new race of Time Lords to only 12 (though this number would be expanded to well over 60 during the Time War). Some historians speculate that that Rassilon wanted this limit because he didn't want any Time Lord to become immortal and possibly become greater than him. At first only Time Lords were given the gift of regeneration, but later it would be shared with all Gallifreyans. Virtually all records in the Matrix concerning the Timeless Child were later redacted from the Matrix leaving a ficticious history about the Immortality Virus being created by the Biosynthesist Thremix.

Modern Gallifreyan bodies are filled with an imprimature of self-replicating/regenerating bio-genetic molecules (sometimes known as the Immortality Virus, the Legacy of Rassilon). These permanently carried nanites work ceaselessly to repair and prune damaged and malformed cells. They also clean out arteries if too much fried food is eaten. Because of this it takes hundreds of years for a Gallifreyan to show signs of aging. Gallifreyans should avoid primitive germ decontamination technology as these 'germs' are half of the things that keep them alive.
Gallifreyans usually recover from unconsciousness faster than humans and are immune to Dalek Nanogenes. The biogenic molecules allow the body to dispose of foreign objects and implants fairly quickly. The molecules are a variation of symbiotic nuclei and (probably using sonic waves) gives all Gallifreyans a symbiotic self-renewing cell structure. The biogenic molecules are aided by temporal platelets which cluster around any wound, accelerating time in that area to speed the healing. Gallifreyan's with only one heart will find their healing rates greatly slowed. If a Gallifreyan's symbiotic cell structure was ever deactivated they will not be able to regenerate.

When exposed to
extreme pain or a sufficiently strong audio-visual barrage, a Gallifreyan will automatically retreat into a healing trance. With some training, it is also possible to voluntarily retreat into a healing trance.
The mind will essentially switch off, and body will begin drawing large amounts of heat into the core of the body from the outside world. This thermal energy might have something to do with entropy manipulation, or perhaps it is used to power the biogenic molecules. Depending on the severity of the wounds, this heat transfer can cause the body's temperature to drop so far below zero that frost forms on the skin. Only one heart will continue to beat about once every 10 seconds. They will appear dead to most humanoids, but other Gallifreyans can tell they're alive. Using the trance, a fall from over 200 feet can be survived without losing consciousness or seriously breaking any bones. This is accomplished by a combination of bone relaxation and cellular break down and regeneration (similar to what happens in larval pupa). A healing trance allows most injuries (such as burns and diseases) to be healed in a day. A broken leg can heal in anywhere from a few hours to 4 days depending of the severity of the break. Most nonlethal bullet wounds heal in a day (the bullet is ejected from the body). Bullet grazes heal in a few hours as does the damage from some energy pistols. A combination of a bullet hole through the frontal lobe, a broken nose, jaw, femur, and collarbone will take a Gallifreyan 6 months to heal. While in the trance they can metabolize many types of poisons and drugs using Detox. It can take 23 days in a coma to deal with Polonium 210 poisoning. They can selectively regenerate specific organs while in the trance and (given several months) a Gallifreyan can grow a new heart (should one of their originals be removed). It might be possible for them to grow new limbs. If kept alive, a Gallifreyan’s severed body part can be used to detect whether that specific Gallifreyan is in the area.

These rates of healing can be enhanced if the Gallifreyan is kept near (or inside) a TARDIS. Gallifreyan Medical Science has devices that can heal skin wound a few inches across in under half an hour. Bruises and cuts from a major brawl can be healed in 15 minutes. Their science can clone Gallifrey limbs from a single spit sample. It takes 2 days or less to create a hand. The patient must be sedated to have the limb re-attached, and the process leaves a thick pink scar at the seam. Unfortunately they can not regrow lost hands or limbs on humans because their technology isn't advanced enough yet. This is one of the few medical problems they haven't solved. For extensive body repair the patient's mind can be held in the Matrix for the duration of treatment. Gallifrey technology can't heal micro aneurysms inside a brain stem.

At age 8 every Gallifreyan is exposed to the
Untempered Schism which surrounds their bodies with bio-plasmic fields of regenerative cronon energy. These fields protect a Time Lord as they travel from one time stream to another. Without exposure to the Untempered Schism Gallifreyans wouldn't have the energy for regeneration a Gallifreyan would eventually age and die. The fields of a Time Lord will protect their clothes (and the stuff in their pockets) from temporal shifts. These bio-plasmic fields have to be very active to adapt to the trauma of Regeneration. So much so that if a member of a lesser species is exposed to a Gallifreyan for several months the bio-fields will 'infect' them providing the same protection from the time stream, rejuvenating their cells and replace their telomeres. As a result the primitive will age very slowly and live for centuries. If this alien was to leave Gallifrey they will start to age at the rate of a year for every day.

It is possible, for a Gallifreyan to divert some of the
chronon energy of their future regenerations from their bio-plasmic fields into a artron power cell or even another Gallifreyan. Such donations reduce the life-span of the Gallifreyan and, if the donation is big enough, runs the risk of causing error or even failures of future regenerations. When done with another person this process is known as genetic fusion, and allows the other Gallifrey to trigger the healing part of a regeneration, without fulling transforming into a new body. The transfer is not very efficient. A significant amount of regenerative energy is required to heal a broken wrist, and healing blindness could leave the Gallifrey missing some limbs or stature in a future regeneration. Healing a major bullet would use up an entire incarnation, and it would take all of the donor's unused regenerations to heal a major mortal wound. Even with Gallifreyan gene-splicing science this is still an imperfect and unreliable technique.

With the help of the biogenic molecules, a single body can last over 1,200 years. But if the body is subjected to great stress, such as a severed limb, extreme illness,(or perhaps extreme boredom) the Limbic (or Lindal) Gland releases the hormone Lindos to trigger Regeneration. It is also possible for some (all?) Time Lords to will their own regeneration without stress or injury. While there is significant chance of regenerative failure when a regeneration is trigged by damage, a voluntary regeneration has a very high chance of success. Gallifreyans are educated in how to control their regenerations at their chapter's academy. By enacting the proper meditative techniques a Gallifreyan can temporarily delay the triggering of their regeneration by at lest a couple weeks. Chemical and telepathic signals from a trained Gallifreyan can be used to guide or even force regenerate someone who is badly wounded (but not somebody who is conscious and refuses to regenerate). Unfortunately, temporary post-regenerative amnesia often occurs if a regeneration is delayed too long after suffering a mortal wound (this assumes they don't die first). This amnesia can last for several hours and give the Gallifreyan a paranoid and fearful attitude. Adrenalin can help with recovery from the amnesia. 

Gallifreyans wGallifreyans who are exposed to the vacuum of space for several minutes, are unlikely to regenerate. But if they do they will continue to regenerate over and over as the lack of air kills them until their cycle is exhausted. Under such circumstances mutations are likely as the body tries to find a form that can exist there. Likewise, Gallifreyans who have had both their hearts punctured or destroyed, suffer a disabling attack on their entire nervous system, or suffer a direct hit by a Dalek Neutraliser can not usually regenerate. It is possible to regenerate from a glancing hit by a Dalek Neutraliser. Large amounts of anaesthetic gas can delay or even stop the triggering of a regeneration. Some types of radiation exposure can interfere with or prevent regeneration. Regeneration after decapitation is unlikely but possible. If successful, the Gallifreyan will grow a new head (that will probably have the same memories as the original).  Even if a Time Lord has had both hearts and all three brain stems stopped and been given a cellular shockwave to abort their regeneration there is still a remote possibility that life could be renewed in the body sometime in the next thousand years. This is because the individual cells in the corpse will spend days trying to regenerate.

Once triggered, the Lindos hormone travels throughout the Gallifreyan's body. The subject will begin to feel weak (especially if this is his first regeneration). As the body prepares to lose solidity, there will be a moment of hallucination (that can seem like hours to the Gallifreyan). At this point the Reset begins. The self-replicating biogenic molecules heal the body of its wounds, viruses, poisons, and aging, restoring its youth. In most cases, once all the cells have been healed, the regeneration of the body will proceed immediately.

With great effort, it is possible for a Gallifreyan to temporarily delay the second phase of the regeneration for 
at least 30 minutes and occasionally a few hours, during which time they will slowly grow weaker as their body fails. Doing so can sometime cause minor alterations the Gallifreyan's physical appearance. Beyond this point the regenerative energy will have to be used or it will kill the Gallifreyan. If the second phase of the regeneration finally does go forward the result will generally be a 'slow explosion' regeneration that can cause a lot of collateral damage.  If the regeneration was triggered by an injury, and a suitable bio-matching receptacle (a spare hand that had been amputated for example) is available, the Gallifreyan can abort the Regeneration after the Reset process is complete by siphoning off all the extra energy into the receptacle. This is a rare occurrence as regeneration was never intended to be used to heal injuries (and bio-matching receptacles are rarely available).

After healing, the regeneration proceeds and the subject's body (and to a lesser degree the mind) will be completely restructured. The extra third strand of the tri-strand DNA was added by Rassilon to hold the elements that make Regeneration possible. This strand stores the regenerative information within the Gallifreyan's bio-plasmic fields that surrounds their bodies. Empowered by the cronon energy from their exposure to the Untempered Schism, the regenerative information is conveyed to the biogenic molecules via a bio-language called Nucleolingua Symbiotica. If the subject is killed after the healing reset, but before the restructuring of the body, the rengeration is likely to fail and leave the Gallifreyan dead.

When a regeneration does occur the permanently carried self-replicated biogenic molecules rebuild the body in a violent biological eruption of artron energy. Normally this energy comes from the Lindos hormone, though other sources of artron energy can be used as well. The process usually begins with the hands. Using this energy every molecule in every cell is adjusted, displaced, rearranged causing a complete renewal and healing and consuming the rest of the energy. The burst of energy from a regeneration causes that area to be partially time locked. So, no matter how a Gallifreyan's history is altered, it will have a tendency to be put back on track when they reach the moment of their regeneration. Regeneration also restructures the biodata of the subject, thus it could affect the subjects past as well as its future. Because of this some Time Lords will catch glimpses of their entire past and future during the final tremors of their regeneration. This is known as a Memory Vortex. Most regenerations take between 10 seconds and 2 minutes and release a great deal of heat.
The appearance and speed of the regeneration can take several different forms:
  • The White Light: A white glow surrounds the body as the transformation occurs. This is common when old age has triggered the regeneration
  • The Morph: The body will physically distort as it discharges several arcs of electricity. Probably caused by having the regenerative process being slowed by an external force.
  • The Blur: The flow of light passing near the regenerating body will be distorted blurring the subject.
  • The Swirl: A very quick regeneration (sometimes as lasting as little as 10 seconds) that can be triggered if the Gallifrey feels they are about to suffer a leathal attack.
  • The Slow Explosion: A slowly building glow will be released by the Gallifreyan over a couple of minutes. Usually caused by the Gallifrey trying to delay the regeneration.
  • The Explosion: Large amounts of excess regenerative energy is released by the Gallifrey, possibly damaging the surrounding area.
  • The Reverse Explosion: Excess energy is released in a massive blast during the early healing process, allowing the final transformation to occur quickly and quietly.
In any event, Regeneration is an exhilarating experience akin to driving a car very very fast. Some find the event to be filled with images of horror from their own past, and have compared the regeneration experiance to a bad LSD trip. During this time some of the old neural pathways close and many new ones are created. A blinded Gallifreyan will regain their sight after after a regeneration if the neural pathways controlling his sight are intact. Even damaged synapses are repaired. At the first regeneration the nanomachines are programmed to build into the new body a number of improvements and backup systems including a new heart. For this reason the first regeneration is usually the most painful. At the end of the regeneration the comatose Gallifreyan is awakened with by an automatically triggered electroencephalographic shock. But a particularly stressful regeneration will leave the Gallifreyan unconscious for over an hour. Gallifreyans typically have no memory of the exact moment of their regeneration. It takes about 10-60 minutes for the body to "gel" completely which allows Gallifreyans of New Blood Houses some time to try various genetic configurations and chose their physical forms. Things like hair length can sometimes alter multiple times over the next few days due to regeneration. If a Gallifreyan develops an immunity to a virus that immunity will persist in each new incarnation.

When a child regenerates their new body is also a childe’s body. However it is very dangerous for Gallifreyans who haven't passed First Maturation (ie teenagers) to regenerate. For this reason it is usually forbidden for Gallifreyans to regenerate until they are 500 years old.

For most Gallifreyans of the Old Blood Houses the form of their body is out of their conscious control, and instead picked by their subconscious. Gallifreyans of some houses tend to keep the same racial and sex characteristics through most, but not necessarily all, of their incarnations. Occasionally two different Gallifreyans will end up with bodies that look the same. This has been witnessed on at least 1 (or 2, or 3) occasions. On other occasions Time Lords have copied the bodies of humans they have seen. Under some circumstances an adult Gallifreyan can regenerated into a childe. It is possible for a Gallifreyan's sex to change during regeneration if the regeneration particularly traumatic (often if the Gallifreyan regenerates by choosing to committing suicide). This is known as a Sex Change Regeneration. Approximately 10% of Gallifrey's population is female.

Gallifreyans
from Newblood Houses have amazing control over there regenerations which allows them to try on several different genetic templates (and appearances) during the first 60 minutes of a regeneration. This technique can be taught with some success to Gallifreyans from the Old Blood Houses. Some are even capable of temporarily regenerating their genetic makeup enough to fool some types of gene scanners without inducing a regeneration, but this consume a lot of chronon energy.

While
Regeneration often causes temporary memory gaps the new body should have all the same memories. However, because of the new personality, he will tend to draw different conclusions from those remembered experiences. After regeneration, Gallifreyans often don’t know which skills they’ve kept and which ones’ they’ve ‘lost’ until they try to use the skill.  While most skills remain the same, it appears that many dexterity based skills need to be "relearned" (at a fairly quick rate) due to the difference in body design. A Gallifreyan's handwriting remains more or less the same throughout all of their incarnations. After violating the 7th Law of Time, it’s possible that any regeneration blocks any lingering memories a Gallifreyan has of events from his own future.

Due to the chemical changes in their brain, and the opening and closing of neural pathways, the new body will often appear to have a different personality. This personality is often heavily emphasized for the first few hours. In truth, the new personality is simply the expression of a different aspect of their fundamental personality.

A copy of the previous personality is stored in the memory space for eventual transfer into the Matrix. Officially each copy is kept 'sleeping' in a mental 'room with no doors.'
In actually fact, past incarnations often resent being locked away and wish they could have lived longer. In very rare cases of Regenerative Dissonance the copies of the previous personalities are left active and have just as much control over the Gallifreyan as the current personality. Most Gallifreyans with this condition quickly arrange a permanent suicide - usually before their seventh incarnation, however the Time Lord sometimes known as the Twelve successfully reached her 12th incarnation. Some Time Lords of the first rank can intentionally achieve Retro-Regeneration and temporarily summon the skills and personality of a former incarnation. A TARDIS's Telepathic Circuits can help a Time Lord achieve this. As the number of personalities build up in the subconscious the Gallifreyan mind can risk breaking under the strain. There is also Gallifreyan Technology that allows a Time Lord to borrow biodata from their own future to overcome a current physical or mental disability for 20 minutes. But it dangerous to use. Possible complications include: all future incarnations having the same disability, the loss of the ability to ever regenerate, or burning out the user’s brain and killing them at the end of the 20 minutes.

The random nature of regeneration terrifies most Old Blood Gallifreyans. Until recently Regeneration was still a relatively risky procedure. Major injuries can lead to a potentially fatal regenerative collapse. During regeneration their immune systems are comprimised, making their biodata vulnerable to paradox viruses or other types of minor temporal paradox which can lead to all sorts of complications. While regenerating a Gallifreyan's body might incorporate foreign materials it comes in contact with. Sometimes this would lead to development of severe allergies (for example to gases in the praxis range or extremely humid air). If the contamination consisted of biodata, the body might incorporate the foreign material allowing them to change species. Thus a Gallifreyan could regenerate and find himself to be half human. It is also possible for them to regenerated in an animal like a talking dog (which could change breeds with every subsequent regeneration) or a cat. Damaged genetics during a regeneration can leave the subject with unstable DNA leading to cellular degradation. This requires frequent consumption of the artron life energy of others to survive, but with each live consumed the period of stability shortens. Other legends tell of regenerations that had only regenerated half of the body (which can happen if the subject regenerates in a strong time dilation field), regenerations where the body was changed but not the brain, regenerations that turned the subject inside out, regenerations that reverted the Gallifreyan into a time-tot and other monstrous variations. There are rumors and heresies that, at one point in Gallifrey's history, a Shadow House existed which would hold Gallifreyans whose regenerations have failed in some way. These problems were only corrected within the last several thousand years. The Free Time organization created the Dogma Virus.  This virus would remain dormant in Gallifreyans until they regenerated, at which point the subject’s new incarnaiton turned into a violent mindless being.

After regenerating most Gallifreyans will retreat into a healing trance for up to 6 hours. A Gallifreyan's blood pressure can drop to 70/70 millimeters of mercury during this time. Waking a Gallifreyan from this healing trance can cause a neural implosion, which significantly increases the amount of time the trance will be needed. While sleep and healing trances are perfectly safe, being violently rendered unconscious shortly after a regeneration can induce a second regeneration. Within the first 15 hours of regeneration a Gallifreyan will still have enough residual cellular energy to cause several unpredictable effects. This energy can be used to heal many types of physical damage. Deadly falls, and multiple bullet wounds will heal near instantly, and they might be able to survive a gun shot to the head. Recovery is fast enough that even severed arteries generaly won't have time to bleed. They can even regrow a severed body part, such as a hand. The energy can be discharged causing destructive effects to people or objects that are hit by it. The new body part might be designed to prevent whatever caused the loss of the original.  
Shortly after regeneration Gallifreyans will often experience bursts of superhuman strength and speed while the new body stabilizes.

Regeneration is quite energy draining and Gallifreyans will often need to consume large meals to return to their normal biological energy levels.
Because their body is still working on overdrive many Gallifreyans also experience disorientation and confusion due to the ambient complexity of the area. The ambient complexity consists of the number of sapient minds in the local area (which generate psionic fields) and the amount of technology (which generates electro-magnetic fields). If the Gallifreyan regenerated in an environment with excessive ambient complexity it can cause a Regenerative Failure. And even after the regeneration has been completed, ambient complexity can causes erratic and volatile mood changes. While extreme heat combined with adrenalin can temporarily stabilize a newly regenerated mind and recover from amnesia, the only reliable way to halt the failure is to move the subject to a zero environment. Once in a Zero Room a Time Lord can enter a healing trance while waiting for their body to stabilize. It is very rare that the environment on Gallifrey or inside a TARDIS will trigger regenerative failure and its almost unheard of inside the dome of the Capitol. In some cases Post-Regenerative Trauma can cause severe personality instability. This can even leave them permanently psychotic and under the control of the dark side of their mind. In most cases the Gallifreyan's mind will synchronize properly within 4 days returning their strength, reflexes, and personality to normal (for their new incarnation). Sometimes in the absence of a Zero Room the subject never synchronizes properly. Both Metamorphic Symbiosis Regenerators and Zero Rooms can assist with regenerative trauma and ambient complexity. Anesthetic can delay or destroy the regenerative process and cause post-regenerative amnesia.

For all these reasons regenerations are usually planned months to years before the actual event. A low-grade telepathic field (like the inside of a TARDIS or a boost generated by another Gallifreyan) is essential to ensure survival during a regeneration especially if the subject has suffered radiation damage. Without suchy assistance an injured Gallifrey runs the risk of the regeneration aborting halfway through leaving the subject looking like some sort of multi-limbed monster, and destroying their ability to regenerated again.

Going through 7 regenerations in less then 700 years is considered to be incredibly wasteful, but some seedy Gallifreyan Cardinals hang themselves to get rid of extra regenerations. This is considered to be a dangerous hobby. For these reasons their's a fair amount of "regeneration politics" among certain factions on Gallifrey. These focus on issues of class, gender, and species. Sex Change Regenerations are possible, (probably by splitting a males diploid cells into haploids). Each body is referred to as an "incarnation" or a "life-span". Public discussions of regeneration among Gallifreyans appears to be similar to sex amongst humans (i.e. not good table manners). Regeneration is considered to be a private matter - not to be witnessed by others (artificial or otherwise) and are generally conducted in a very quiet location. However a loom automatically records the genetic metamorphosis every time one of its cousins regenerates. 

Each body can last centuries. While Gallifreyans only need to regenerated every thousand years or so, it is possible, with rejuvenation and care, to get 10,000 years out of each incarnation. Most Gallifreyans will notice their bodies slowing down and reduced stamina after two to three hundred years. CIA Field Agents tend to go through a life-span approximately every 150 years. It should also be noted that the last few life-spans generally don't last as long as the earlier bodies. This is because elderly Gallifreyans tend to regenerate more often in an attempt to dispel physical and mental malaise. With every regeneration more of the nucleolingua symbiotica is consumed. Thus it is possible to determine how many remaining incarnations a Gallifreyan has by measuring the amount of Nucleolingua Symbiotica remaining in the tri-strand DNA. The last few regenerations of a cycle appear to produce much more excess energy, enough to severely damage a TARDIS control room.

As the number of personalities build up in the subconscious the Gallifreyan mind eventually risks breaking under the strain. Because of this tendency towards madness, Tecteun engineered it so that the nucleolingua symbiotica can only divide 12 times before the biogenic molecules become unstable and decay - limiting a Gallifreyan to 13 bodies. As a result Gallifreyan minds and bodies can only withstand the strain of 12 regenerations. If a Gallifreyan suffers a severe enough injury in his 13th body, a regeneration will be triggered, but its inevitable failure will kill the subject. Some historians speculate that that Rassilon set up this automatic decay because he didn't want any Time Lord to become immortal and possibly become greater than him. During the Time War the number of regenerations availible to a Time Warrior would be expanded safely to well over 60.

If a Gallifreyan's morphic print is destabilized it can lead to them being physically regressed back through previous incarnations. This occurs because the Gallifreyan's body is instinctively trying to find a stable morphic print. The interior of TARDIS or similar stabilizing facility such as a Metamorphic Symbiosis Regenerator, can hault this phenomenon, and a personal morphic stabilizer can be used to allow the Gallifreyan to move freely.

With rejuvenation and care a Gallifreyan could get up to 10,000 years of mobility out of each incarnation. And technically Gallifreyans can force themselves to stay alive indefinitely, making them immortal except for accidents. But by age 12,000 most Gallifreyans are suffering from severe senility and forgetfulness, for this reason, they usually choose there final Death Day between 7,000 and 12,000 (usually at about age 10,000). Triggering a 13th Regeneration might be the accepted way that Gallifreyan's end their lives.

It is possible to surgically implant a new regenerative cycle by manipulating the Nucleolingua Symbiotica, but this can only be done with the permission of the entire High Council. Such a process requires cryogenetic extraction to generate a elysian field.  Such a field can even regenerate a Gallifreyan's who has exhausted their capability of regenerating, while simultaniously bestowing an entirely new regeneration cycle. This is probably achieved using a Metamorphic Symbiosis Regenerator (which can provide unlimited regenerations). The regeneration cycle can also be renewed by recharging the chronon energy of their bio-plasmic fields. This recharging requires a massive amounts of carefully modulated and controled chronon energy. Renegade Gallifreyans have been know to renew their regenerative cycle by "Jumping Looms" (being reborn into a new Family), though this process generally result in a loss of most of the renegade's memories. With all of these techniques, a Time Lord might be able to regenerate many more times, but probably at the cost of their sanity. If Gallifreyan receives a new cycle of regenerations, the gap between the healing reset and the actual first regeneration tends to be on the order of several minutes instead of seconds. This delay will cease once the new cycle is properly broken in.

A catalytic
distillation and extraction chamber can be used to collect up a Gallifreyan’s life-force (and thus steal their future regenerations) if it is applied as soon as the Gallifreyan begin to regenerate. In theory it is also possible to extract an existing regeneration cycle from a Gallifreyan using surgery. To do so the relevant chains for each incarnation would have to be isolated and drawn off – removing that regeneration. This extracted cycle could then be implanted in a new subject. Some have speculated that it might be possible to bypass Rassilon’s death trigger by distilling the corrupted nucleolingua symbiotica of a Gallifreyan in his 13th body.
A Genetic Manipulation Device (GMD) appears to use the same principles of regeneration only the technology is external to the subject. Using a sonic micro-field manipulator the GMD creates hypersonic waves. These sound waves create a state of resonance in the subject, which destabilizes the subject's cell structure and DNA. If the subjects biological code is programed into the manipulator, a metegenic program can then hack into the subjects genes, manipulate the coding in the protein strands, and program them to regenerate. This technology can also be used to prevent regeneration or hyper-age a Gallifreyan. A GMD can be built into a Laser Screwdriver to be used as a weapon.
For information of the education, life, and death of Gallifreyans, see this page: Loom to Tomb
For information about the biology, training, and powers of the Time Lord elite of Gallifrey see this page: Time Lords