64 HEEEDITY AND SELECTION IN SOCIOLOGY 



germ-plasm is unknown, and it is useless to speculate about it. 

 We can only say that an infinite number of relations connect tie 

 determinants of tlie germ-plasm with one another. We are here 

 in the world of the infinitely minute, and it is difficult to form a 

 conception of the rhythmic movements of the elementary living 

 particles. But we may say that a priori no valid objection can 

 be raised against the conception which sees in the germ-plasm a 

 heterogeneous substance formed by heterogeneous determinants, 

 each determinant or group of determinants standing in definite 

 relation to a given part of the finished organism. Only those 

 variations which arise from the germ-plasm are transnoissible by 

 heredity. The facts revealed, alike by recent histological re- 

 search and by observations on the phenomena of heredity, are 

 in harmony with this theory of evolution and development. 



