494 PHILOSOPHIC ZOOLOGY 



remarkable results bearing on the theory of heredity have been 

 obtained by applying the principles of Mendel, but these cannot 

 be discussed here, especially as there are difficulties in the way 

 of conducting similar experiments on animals. 



Readers who wish to acquire further knowledge in matters 

 relating to biological theory would do well to consult the works 

 of Darwin, Wallace (especially Darwinism)^ Romanes (Darwin 

 and After Darwin], Weismann, Lloyd Morgan, Verworn (General 

 Physiology), E. B. Wilson (The Cell in 9 Development and Inheri- 

 tance), T. Hunt Morgan (Evolution and Adaptation), and Mendel 

 (Principles of Heredity). A good preliminary acquaintance with 

 the subject may be obtained .by reading Arthur Thomson's 

 Science of Life. 



