THOMAS WILLIS 61 



vessels, and the construction of the eye, including the retina. Galen 

 speaks of Herophilus as having a very intimate knowledge of the 

 anatomy of the nervous system. The term, "torcular Herophili" 

 signifies the "press" or dilation at the junction of the superior longi- 

 tudinal, lateral and occipital sinuses first described by Herophilus. 

 Herophilus and his associates performed vivisection upon condemned 

 criminals. Not only did medicine progress during this early period 

 (about 300 B. C), but literature, philosophy, mathematics, natural 

 history and astronomy flourished as well under the patronage of 

 Ptolemy. A great part of the record of this fruitful period was lost 

 during the seventh century of the Christian Era, with the destruction 

 of the great Alexandrian library. 



"The Brain the seat of Thought and Sensation:" Galen, A. D. 

 160, overthrew Aristotle's theory in regard to the brain and showed 

 it to be the seat of thought and sensation. Aretaeus (170 A. D.) 

 taught that the brain controlled the muscular movements of the body 

 by means of nerves originating in the brain. He recognized the 

 crossing of the nerves so that injury to one hemisphere pro- 

 duced paralysis on the opposite side. If injury occurred in the 

 cord below the medulla the paralysis was on the same side as the in- 

 jury. The seat of the soul was, however, in the heart. 



Andreas Vesalius (1514-1564) declared that the "brain in ap- 

 propriate structures, and in organs properly subserving its work 

 manufactures the animal spirit which is by far the brightest and 

 most delicate, and indeed is a quality rather than a natural thing. 

 * * * Nerves serve the same purpose to the brain that the great 

 artery does to the heart." The nerves he regarded as the "busy at- 

 tendants and messengers of the brain." Vesalius, however, is free in 

 the use of such terms as "vital soul," "vital spirits," "animal spirits," 

 which meant so much to the physiologist of his day and so little to 

 us of the twentieth century. While these meaningless terms make a 

 great deal of his work unintelligible, yet there abound throughout 

 gleams of truth as we understand it today. He showed that by sever- 

 ing a nerve or by ligation it was possible to abplish_the action of 

 the nerve upon the muscle. Regarding the brain he says : ~**But how 

 the brain performs its functions in imagination, in reasoning, in 

 thinking and in memory, I can form no opinion whatever." 



Nearly a century later we come to the conclusions of von Hel- 

 mont and of Descartes which were much less to the point than the ex- 

 pressed opinions of Vesalius. One placed the seat of the soul in the 

 pylorus ; the other in the pineal gland. 



Malpighi devoted much attention to the histology of the nervous 

 system but said practically nothing about the functions of the nerves. 



Thomas Willis: Perhaps the most important investigator of 

 the seventeenth century into the anatomy and physiology of the 

 nervous system was Thomas Willis. He was born in Wiltshire, Eng- 

 land, in 1621, educated at Oxford where he graduated with the degree 

 of M. A., 1642. He eventually entered upon the study of medicine 

 and on graduation was appointed to a professorial chair in Oxford. 

 Here he taught, practised medicine and pursued his scientific re- 

 searches. In 1666 he located in London where in the language of a 



