388 Coe — A Century of Zoology in America. 



sense, is the study of the geographical distribution of 

 animal species and larger groups. 



Paleontology. — The geological succession of organisms 

 embraces a field where zoologist and geologist meet. 

 Most of the studies in this subject, however, have been 

 made by geologists. 



Biometry. 



Since Darwin's theory of evolution postulated the 

 origin of new species by means of natural selection, it 

 was obviously necessary in order to apply a critical test 

 to determine the precise limits of a species. It was, 

 therefore, proposed to subject a given species to a strict 

 examination by the application of statistical methods to 

 determine the range of variation of its members and the 

 extent to which the species intergrades with others. 

 Other problems, particularly those concerning heredity, 

 were treated in similar manner. This branch of biolog- 

 ical science was particularly developed by the English 

 School, led by Sir Francis Galton, followed by Karl 

 Pearson and William Bateson. 



In America the methods of biometry have been utilized 

 extensively by Charles B. Davenport, Raymond Pearl, H. 

 S. Jennings and others in the solution of problems in 

 genetics and evolution. Their work shows the great 

 value of critical statistical analysis in the interpretation 

 of biological data. A thorough training in mathematics 

 is now found to be hardly less important for the biologist 

 than is a knowledge of physics and chemistry 5 for the 

 science of biometry has become one of the most important 

 adjuncts to the study of genetics. 



Comparative Anatomy and Embryology. 



Comparative Anatomy— Upon the foundations laid 

 down by Cuvier a century ago the present elaborate 

 structure of comparative anatomy of animals, both verte- 

 brate and invertebrate, has been developed. Vast as is 

 the present accumulation of facts and theories many 

 important problems still await their solution. Jeffries 

 Wyman was long a leader in this field, where many 

 workers are now engaged. 



Embryology. — The embryological studies, so bril- 

 liantly begun by Von Baer early in the nineteenth cen- 

 tury, are still in progress. They have now been entended 



