26 An Examination of Weismannism. 



Again, if for the sake of distinctness we neglect 

 all these far-reaching deductions from his theory of 

 heredity whereby Weismann constructs this elaborate 

 theory of organic evolution, and fasten our attention 

 only upon the former, we may briefly summarize the 

 fundamental difference between his theory of heredity 

 and Darwin's theory of heredity thus. 



Darwin's theory of heredity is the theory of Pan- 

 genesis : it supposes that all parts of the organism 

 generate anew in every individual the formative 

 material which, when collected together in the germ- 

 cells, constitutes the potentiality of a new organism ; 

 and that this new organism, when developed, resembles 

 its parents simply because all the formative material 

 in each of the parents has been thus generated by, and 

 collected from, all parts of their respective bodies. 

 Weismann's theory of heredity, on the other hand, is 

 the theory of the Continuity of Germ-plasm : it supposes 

 that 110 part of the parent organism generates any of 

 the formative material which is to constitute the new 

 organism ; but that, on the contrary, this material 

 stands to all the rest of the body in much the same 

 relation as a parasite to its host, showing a life inde- 

 pendent of the body, save in so far as the body supplies 

 to it appropriate lodgement and nutrition ; that in 

 each generation a small portion of this substance is 

 told off to develop a new body to lodge and nourish 

 the ever-growing and never-dying germ-plasm — this 

 new body, therefore, resembling its so-called parent 

 body simply because it has been developed from one 

 and the same mass of formative material ; and, lastly, 

 that this formative material, or germ-plasm, has been 

 continuous through all generations of successively 



