128 PROGRESS OF SCIENCE. 



of simple species through anatomy and physiology only. 

 The influence of his teaching that is, of a body of physio- 

 logical doctrines was equally extensive and durable. He 

 also raised surgery from a poor empirical art to a noble 

 science by initiating striking improvements. He discovered 

 the electric nature of the Torpedo's commotions ; showed the 

 electric nature of the Gymnotus ; explained the respiration 

 of birds fully; studied the cetacea; and one of his main 

 claims upon our gratitude founded the Hunterian Museum, 

 one of the most beautifully classified collections in existence 

 each organ being displayed throughout its stages of 

 development from its lowest to its most complicated form. 

 Hunter was the most famous successor of Harvey as a 

 physiologist. It should be mentioned that the Italian 

 Morgagni (1682 1771) preceded Hunter in the field of 

 pathological anatomy and left invaluable contributions to 

 science, although he did not formulate the broad generalisa- 

 tions which make Hunter famous. 



1731 1802. Darwin (Erasmus), adopting Buffon's theory 

 of the origin of species by evolution, assigned the main cause 

 of animal development to the actions, wants, and habits of 

 the animals. This is the germ of the theory of organic 

 development; it only wanted the doctrine of natural selection 

 to anticipate Charles Darwin in all points. "As the earth 

 and ocean," says Erasmus Darwin, " were probably peopled 

 with vegetable productions long before the existence of 

 animals, and many families of these animals long before 

 other families of them ; shall we conjecture that one and the 

 same kind of living filament is and has been the cause of 

 all organic life ? " In " Zoonomia/' we read : 



First, forms minute, unseen by spheric glass, 

 Move on the mud, or pierce the watery mass ; 

 These, as successive generations bloom, 

 New powers acquire, and larger limbs assume ; 

 Whence countless groups of vegetation spring, 

 And breathing realms of fin, and feet, and wing. 



" When we revolve in our minds," says Erasmus Darwin, 

 "the great similarity of structure which obtains in all the 

 warm-blooded animals, mankind included, one is led to 



