40 



TEXTBOOK OF ZOOLOGY 



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 

 observatiojis 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 



Fig. 10. — William Harvey (1578-1657), father of physiology. (From Garrison, 

 History of Medicine, published by W. B. Saunders Company.) 



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 

 in capillaries, studies on glands, and his work on the structure and 

 metamorphosis of the silkworm take rank with outstanding con- 



