WHAT EVOLUTION IS 29 



2. FROM EMBRYOLOGY 



The science of embryology deals 

 with the growth of animals from the 

 tgg to the adult, and this science, 

 though of comparatively recent ori- 

 gin, has had an important bearing on 

 evolutionary problems. It is a com- 

 monplace that, in the development of 

 any animal, the creature does not 

 start life as a miniature of what it is 

 finally to be and then slowly enlarge 

 until it reaches adult proportions, but 

 it begins life in a state very unlike its 

 adult condition and only gradually 

 assumes an outline that is associated 

 with its final form going through a 

 series of changes, often very pro- 

 found, till it finally arrives at its ma- 

 ture state. 



Most common animals afford ex- 

 amples of this kind of growth. 



