It is rather easy to understand, then, that a medical school arose in connection with this scientific university, and that it did excellent work. The collections of Aristotle contained many illustrations which served as the basis for zoology, botany, comparative anatomy and probably even comparative physiology. The Ptolemys were very liberal and allowed dissection of the human body, so that human anatomy developed from a definite scientific standpoint better then ever before. The number of strangers in the town and the rather unhealthy climate of Egypt left many unclaimed bodies. It has always been the difficulty of obtaining bodies much more than prejudice against the violation of the human body on any general principle, that has been the reason {384} for the absence of human dissection in many periods of the world's history. We object to having the bodies of friends cut up, but we do not mind much if the bodies of those who are unknown to us are treated in that way. So long as men did not travel much there were few unclaimed bodies. With the advent of travel came abundant material for dissection and the Ptolemys allowed the medical school to use it. Two great anatomists built up the structure of scientific human anatomy on the rather good foundation that had been laid on animal anatomy in the foretime. After all, the anatomy of the animal resembles that of man so much that very precious knowledge had been gained from zootomies in the previous ages. These two anatomists were Erasistratos and Herophilos. Both of them studied the brain especially, as might have been expected. For just as soon as the opportunity for dissecting man was provided, this, his most complex structure, attracted instant attention. Herophilos has named after him the _torcular herophili_, and the name he gave the curious appearance in the floor of the fourth ventricle--the _calamus scriptorius_--is still retained. He describes the membranes of the brain, the various sinuses, the choroid plexuses, the cerbral ventricles and traced the origin of the nerves from the brain and the spinal cord, recognizing, according to well-grounded tradition, the distinction between nerves of sensation and motion. {385} He described the eye and especially the vitreous body, the choroid and the retina. He did not neglect other portions of anatomy, however, and his power of exact observation, as well as his detailed study, may be judged from his remark that the left spermatic vein in certain cases joins the renal.