416 A CENTURY OF SCIENCE 



validity is generally incapable of a critical test. But 

 wherever such tests have been possible, the laws of math- 

 ematics, physics and chemistry are found applicable to 

 biological phenomena. 



The number of investigators has now become so great 

 and their activities so prolific that the list and synopses 

 of the zoological publications each year cover upwards 

 of 1000 to 1500 pages in the International Catalogue of 

 Scientific Literature. 



American Leadership. During the first half of the 

 century the progress of zoology in America remained dis- 

 tinctly behind that of Europe. At the beginning of the 

 century the science was farthest developed by the French 

 and English, although Linnasus was a Swede and took his 

 degree in Holland. Under the influence of Von Baer and 

 his monumental treatise on embryology (Ueber Entwick- 

 lungsgeschichte der Thiere, 1828), and supported later 

 by the great physiologist, Johannes Muller, whose "Phy- 

 siologie des Menschen" (1846) forms the basis of modern 

 physiology, the German school forged rapidly ahead and 

 eventually assumed the leadership in zoology, as in sev- 

 eral other branches of science. 



In the latter half of the century the influence of the 

 German universities dominated in a large measure the 

 zoological investigations in America. The reason for 

 this is partly due to the fact that many of our young 

 zoologists, after finishing their college course, com- 

 pleted their preparation for research by a year or more 

 at a German university. The more mature zoologists, 

 too, looked forward with keen anticipation to spending 

 their summer vacations and sabbatical years in research 

 in a German laboratory or at the famous Naples station 

 in which the German influence was dominant. 



With the rise of experimental biology since 1890, how- 

 ever, the American zoologists have shown so high a degree 

 of originality in devising experiments, so much skill in 

 performing them, and such keenness in analyzing the 

 results, that they have assumed the world leadership in 

 several of the special fields into which the science of 

 zoology is now divided. 



