MAIN PATHWAYS AND TENDENCIES 113 



Investigations in these fields have become so 

 numerous that special periodicals have been estab- 

 lished for the publication of researches of animal 

 psychology and of animal behavior. 



Experimental Zoology. This is rather a method 

 of broad application than a subdivision of zoology, 

 and bearing this in mind, it forms a convenient cap- 

 tion under which to introduce several topics as Gen- 

 etics, Mendelian Inheritance, Experimental Morph- 

 ology, Experimental Embryology and Experimental 

 Cytology. 



Genetics. Genetics, or the science of inheritance, 

 has been the scene of great activity, has developed 

 until it stands as a much pursued independent divi- 

 sion of zoology. Experiments on the breeding of 

 plants (corn, wheat, flowers, etc.) and animals have 

 brought great extensions of knowledge regarding the 

 growth and the conditions of inheritance in or- 

 ganisms. 



Mendelism. The whole subject of heredity has 

 been pursued by experimental methods giving rise 

 to a large number of special researches too numerous 

 even to summarize. One feature that has occupied 

 the center of the field is the study of Mendelian 

 inheritance. This is properly a subdivision of 



