He could become any individual he wished to mimic A master face dancer needed to see a person for only a minute to produce a rough similarity Several hours of observation resulted in a likeness which could fool casual acquaintances of the victim Given an opportunity to study the victim for several days, die dancer's likeness would be undetectable (for short periods of time) even by the closest of associates The Tleilaxu endowed the face dancers with these abilities by a combination of rigorous training, embryological manipulation, and incredibly delicate surgery Although the procedures were the most closely guarded of Tleilaxu secrets, the methods were unhidden from the prescience of Paul Muad'Dib and especially of Leto II It is chiefly from the notes made by the Emperor Leto that this entry has been compiled THE MAKING OF A FACE DANCER The production of a face dancer began with the selection of breeders for the candidate the Tleilaxu worked from parents with a heritage of slender build, strength, endurance, fine muscular control, and a height froin 1 65 to 1 68 meters Eggs were joined with sperm in vitro, and the process started with the developing embryo Varying Height In the first five weeks of development, an embryo forms a layer of cefls called the mesoderm, and paired repe-tittoos blocks of the mesoderm form structures that are called somites One may envision a somite diagrammatically as a stack of three blocks with a red one on top, a yellow one below, and a green on the bottom Now imagine the stack to consist of forty to fort) four of these combinations of three blocks stacked one above the other Each of the somites in the trunk will differentiate to form structures the red blocks are the dermatomes, from which the skin and fas-cias will develop, the yellow blocks are the sclerotomes, from which the skeleton develops, and the green blocks are the rayotomes, from which the skeletal muscles develop The sclerotome cells mo\e toward the solid rod called the notochord, where they segregate into alternating dense and loose layers In normal development the dense layer from one somite joins to the loose layer of the next to produce the beginning vertebrae of the spine The vertebrae are at first cartilaginous, but by the ninth week of life begin to turn to bone The ossified vertebrae will be separated by fibrous discs At the ninth week, the Tleilaxu technicians intervened chemically to produce an abnormal overdevelopment of the muscles of die back by stimulating myotome growth, and to produce unusually elastic interverte-bral discs by a selective retardation of some sclerotomes The adult face dancer by stretching the back muscles, could niLrease his height by a maximum of about 15 cm, by constricting the same muscles, the discs could be squeezed by reduce height by a maximum of about 7 or 8 cm These changes could be maintained for some hours, though not indefinitely Even the strongest of dancers needed to relax the back