EVIDENCE FROM DOMESTICATION 41 



zig-zag outer edge, but is entirely absent from the 

 anterior wings of the parent species." 



Other similar, if less striking, examples of change 

 might be described, did time permit; all that can be 

 attempted here is to give an outline sketch of the 

 evidence with a few illustrations, chosen from the 

 many that are available. To present anything like 

 an exhaustive display of the evidence would require, 

 not one course of lectures, but many. The instances 

 selected suffice to show that, when placed under new 

 conditions of climate, food-supply, attacks of enemies 

 and the like, animals and plants, whether domes- 

 ticated or free, may experience very marked changes 

 of size, form and appearance and that species are, 

 in very many cases, if not in all, far from immutable. 

 Often the metamorphosis is so great, that the wild 

 progenitor of many domesticated animals and cul- 

 tivated plants cannot be determined with any degree 

 of certainty. 



The other lines of evidence which are relied upon 

 to prove the theory of evolution are comparative 

 anatomy; embryology, the study of individual devel- 

 opment; palaeontology, the study of extinct plants 

 and animals which formerly existed on the earth; the 

 geographical distribution of organisms, animal and 

 vegetable; finally, experimental investigation. Each 

 one of these methods of research has its particular 

 advantages, as well as its special limitations and 



1 M. Wagner: Die Entstehung der Arten durch raumliche Sonderung, 

 pp. 309-10. 



