378 THE HISTOKY OF THE SCIENCE OF ZO()LOGY 



the different forms had developed by slow but gradual 

 changes from the lowest, or ]jrimitive form. In their 

 general views, Buffon and Laniarck were supported by 

 another eminent French zor)logist, Geoffrey St. Hilaire. 

 But the views of these thi'ee nien exerted little influence 

 during their time, owing to the work and writings of Georges 

 Cuvier. Cuvier (17()9-1832) was a great zofilogist and com- 

 pletely dominated the science of zoologj' for half a century, 

 especially in France, where he lived and taught. He was a 

 profound student of the anatomy of animals and formed a 

 classification of animals founded upon their comparative 

 structm-es. He rejected the idea of the unity of the animal 

 kingdom and held tliat there were four distinct and inde- 

 pendent types of animals, not connected with each other 

 by intermediate forms, living or fossil. 



Nineteenth century. — In 1838 Schleiden enunciated the 

 cell theory for i)lants according to which all ]iarts of the 

 body are built up either of cells or of tissues derived from 

 cells. Closely following him, Schwann propounded the same 

 theor}' for the animal body. In 1827 ^'on liaer discovered 

 the ovum of mannuals, and later, from 1843 to 1846, 

 Barry established the relation of the male reproductive 

 cell (sperm) to that of tlie female repro(hK'tive cell (ovum) 

 l)y actually observing the union of the two, thereby deter- 

 mining the meaning of fei-tilization. 



In the early part of the last half of the century — 1859 — 

 occuri'cd what may fairly be called the most important event 

 in the history of biological science, the pulilication. of Charles 

 Darwin's Origin of Species. Up to this time tlie ideas of 

 evolution advanced In' Buffon, Bamarek, St. Ililaire, and 

 I'^rasmus Darwin had not received geiiei'al recognition among 

 zoologists, to say nothing of the great mass of teachers, 



