182 THE SCIENCE OF BIOLOGY 



condemn evolution itself. It is not strange that the layman, 

 for whom Darwinism and evolution are synonymous terms, 

 believes that evolution has been rejected when he hears that 

 belief in Darwinism is on the wane. He does not understand 

 that what is thus meant by Darwinism is not evolution, but 

 the proposed cause of evolution natural selection. This 

 point may not seem vital, but those interested in biological 

 science frequently find the situation used to support claims 

 that the entire concept of organic evolution has fallen into 

 disrepute. There are many, even to-day, who rejoice at 

 anything which appears to weaken this major generalization 

 of biology. 



The more important lines of evidence for organic evolution 

 may be grouped as follows : 



1. Evidence from Structure is derived from: 



Comparative Anatomy 

 Comparative Embryology 

 Classification 



2. Evidence from Distribution, past and present, is derived from: 



Palaeontology 

 Geographical Distribution 



3. Evidence from Physiology is derived from: 



Fundamental Resemblances in Vital Processes 

 Specific Chemical Resemblance of closely related forms, 

 e. g., Blood Tests 



4. Evidence from Experimentation rests upon : 



Unconscious Experimentation upon Animals and Plants since 

 their Domestication 



Conscious Experimentation of Breeders and of Scientific In- 

 vestigators 



The first three of the foregoing groups consist of evidence 

 that is wholly circumstantial. The fourth is in part experi- 

 mental. The facts of comparative anatomy and embryology 

 are what might be expected if evolution has taken place. 

 Without evolution such facts are meaningless. Classifica- 

 tion, since it is based on structure, is a part of this anatomical 



