48 TEXTBOOK OP ZOOLOGY 



an outstanding scholar in the fields of heredity and embryology. 

 He is best known for his theory, that there is continuity of germ 

 plasm from generation to generation. 



Hugo DeVries (1848-1935), a Dutch botanist, brought out the mutor 

 tion theory, which is important to all modern biological conceptions. 

 His idea was that species have not arisen through gradual selection 

 requiring thousands of years for each but by jumps through sud- 

 den, though small, transformations. He is widely known for his 

 experimental studies in plant breeding and genetics, particularly 

 with evening primrose. 



E. D. Cope (1840-1897) was one of the greatest comparative anat- 

 omists of America. He dealt not only with living forms but with 

 fossil materials as well. 



The work of all those mentioned and hundreds of others has given 

 us the background for our present knowledge and grasp of zoology 

 and medicine. History is being made so rapidly in these fields dur- 

 ing the current years that it is difficult even to catalogue the im- 

 portant contributions. It is an extremely active field, particularly 

 in the realm of the experimental endeavors. The printed program 

 for the annual meeting of the American Zoological Society, which 

 is made up largely of titles and abstracts of new papers to be pre- 

 sented, is a small book in itself. 



The works and lives of such prominent pioneer zoologists of the 

 Southwest as Jacob Boll, Gustaf W. Belfrage, Lincecum, Vliet, 

 Walker, "Webb, and others have been described in the recent book 

 by Dr. S. W. Geiser of Southern Methodist University, entitled 

 Naturalists of the Frontier. This book is extremely interesting to 

 read. 



