374 PRESENT PKOBLEMS IN EVOLUTION AND HEREDITY. 



(3) There is a difference of opinion as to whether the paternal and 

 maternal hereditary substances, during- fertilization, are fused or lie 

 side by side; also as to how the substance is distributed through the 

 tissues, whether en masse or by qualitative distribution. 



Heredit.y : 



(4) No connection between the germ cells and body cells is knoww, 

 but the facts of heredity seem to render such a connection theoreti- 

 cally necessary. Several classes of facts connected with reproduction 

 seem to support this theory. 



(5) The facts of heredity sujjport the theory of a continuous and 

 specific form of protoplasm as the basis of repetition of type. 



Evolution : 



(0) The facts of evolution, both in x)resent and past time, point to 

 transformism by definite progression toward new types of structure 

 in succeeding generations, opposing the retrogressive forces of heredity. 



(7) The theory (natural selection) of definite progression by the 

 accumulation of fortuitous favorable variations is found to be not only 

 theoretically improbable, but not to correspond with the observed laws 

 of variation. 



(8) The laws of variation (anomalies) lend support to the theory of 

 hereditary transmission of individual acquired variations, but even this 

 (Laniarckian) theory encounters many difficulties. 



1 think this is as fair a statement as can be made at the present 

 time, and it rests upon a general survey of the whole field. 



