By the labours of Herophilue and Erasistratus nearly every part of the anatomy of the human body was rendered clearer, and many most important discoveries were made. They first determined that the nerves are not connected with the membranes which cover the brain, but with the brain itself, though as yet the distinction of tho nerves from the tendons and other white tissues had not been made out.
The description which Herophilue gave of the brain itself was far superior to those of previous authors : he discovered the arachnoid membrane, and showed that it lined the ventricles, which he supposed were the seat of the soul; and the chief meeting of the sinuses into which the veins of the brain pour their blood still bears the name of Torcular Herophili. He noticed the lacteals, though he was not aware of their use; be pointed out that the first division of the intestinal canal is never more than the breadth of twelve fingers in length, and from this fact proposed for it the name (duodenum) by which it is still called.
Herophilus practised surgery as well as medicine; but it is probable that very soon after his time the division of surgery and medicine into distinct profession. took place. Of his knowledge of medical practice
there is not sufficient evidence in the extracts which Galen makes from his works to enable us to form an accurate idea, and his fame must rest rather on the indirect assistance which he afforded by his anatomical researches than on any immediate addition to the means of curing disease. He does not appear to have drawn many patho.
logical conclusions from his knowledge of the healthy structure, but his observations on the pulse, of which his master Praxegoras had taught him some of the value as a means of discriminating diseases, were important and interesting; and it was he who first showed that paralysis is the result not of a vitiated state of the humours, as was previously imagined, but of an affection of the nervous system.
Herophilus seems to have founded a school which took its name from him. According to Strabo (xii. p. 580), there was a great school of Herophilists in his time established in a temple between Laodiceia and Carura in Phrygia.