32 ESSENTIALS OF ZOOLOGY 



and traditional superstitions are woven together. His work was 

 limited to compilations, and because of the indiscriminate mixing of 

 fact and fancy it is not scientifically valuable. It does reflect the 

 tendency of the time in that scientific observation had given way to 

 speculation. 



Galen (a.d. 131-201), coming in the midst of the ''dark ages" as 

 he does, should be particularly credited for the contributions he 

 made. He was of Greek ancestry but moved to Rome early and 

 became a successful physician. His anatomical studies were made 

 principally from direct observations on elephants, Barbary apes, and 

 swine. During his time it was strictly against the law to make 

 dissections of the human body so he was not allowed this privilege. 

 Unfortunately, Galen did not take advantage of the work of certain 

 of his predecessors who had been privileged to study human bodies. 

 His conviction in the matter of direct observation as a basis of study 

 handicapped him in this respect. His textbook on anatomy became 

 the authority for the next eleven or twelve centuries. 



Andreas Vesalius (1514-1564). — The return of interest in zoology 

 came about through the medical schools. Vesalius was an active 

 young student and was not satisfied to accept the authority of 

 Galen's textbook. Therefore, after beginning his medical education 

 at Brussels, he transferred to Padua where human dissection was 

 then allowed. He later became professor of surgery there. He was 

 the first, since the time of Aristotle and Galen, to prove that direct 

 observation is the only true criterion of knowledge. Vesalius is 

 thought of as the "father of modern anatomy," and his teaching 

 is really responsible for the rapid development of biology and medi- 

 cine following his time. 



William Harvey (1578-1657).— Following closely upon the epoch- 

 making work of Vesalius and inspired by several of his pertinent 

 observations on the anatomy of the circulatory system, William 

 Harvey, an Englishman, began experiments on the movement of 

 blood in the vessels. Galen, Vesalius, and three or four others had 

 suspected a circuit of the blood from the heart to the lungs and 

 return, but Harvey was the first to demonstrate circulation, and the 

 first to arrive at an idea of a complete circulation of all of the blood 

 through a closed system of vessels. This new idea was presented in 

 1628. He also did notable work in embryology. 



Marcello Malpighi (1628-1694) was a famous Spanish anatomist, 

 histologist, and embryologist. His observation of blood corpuscles 



