History of Comparative Anatomy 353 



with a view to getting some light on the location, mode of operation, 

 and nature of the "internal factors." 



A "bird's-eye view" of Biology as it moved forward into this 

 twentieth century reveals the science advancing on three main fronts. 

 One includes Biophysics and Biochemistry. A second consists of 

 Biometry and Genetics, which are investigating the processes of in- 

 heritance and evolution. A third, Experimental Morphology, in- 

 cludes experimental embryology, the study of regenerative develop- 

 ment in adult organisms, and experimentation of any sort calculated to 

 yield information concerning the dynamics of form in living substance. 

 The three fronts, however, are not sharply distinct. They overlap and 

 the subjects are interdependent. Comparative Anatomy, or, more 

 broadly, Comparative Morphology, describing normal form, is the 

 indispensable foundation on which all systematic, physiologic and 

 experimental biologic work must be based. 



