378 THE HISTORY OF THE SCIENCE OF ZOOLOGY 



the different forms had developed by slow but gradual 

 changes from the lowest, or primitive form. In their 

 general views, Buffon and Lamarck were supported by 

 another eminent French zoologist, Geoffrey St. Hilaire. 

 But the views of these three men exerted little influence 

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

 Cuvier. Cuvier (1769-1832) was a great zoologist and com- 

 pletely dominated the science of zoology 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 

 structures. He rejected the idea of the unity of the animal 

 kingdom and held that 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 plants according to which all parts of the 

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

 cells. Closely following him, Schwann propounded the same 

 theory for the animal body. In 1827 Von Baer discovered 

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

 Barry established the relation of the male reproductive 

 cell (sperm) to that of the female reproductive cell (ovum) 

 by actually observing the union of the two, thereby deter- 

 mining the meaning of fertilization. 



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

 occurred what may fairly be called the most important event 

 in the history of biological science, the publication of Charles 

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

 evolution advanced by Buffon, Lamarck, St. Hilaire, and 

 Erasmus Darwin had not received general recognition among 

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



