106 An Examination of Weismannism. 



Weismann's theory regards this substance as owing 

 nothing to the body-tissues, further than lodgement 

 and nutrition. Therefore, while the theory of gem- 

 mules can freely entertain the doctrines of Lamarck, 

 the theory of germ-plasm excludes them as physio- 

 logically impossible, in all cases where sexual repro- 

 duction is concerned. Again, as regards stability, 

 while Darwin's theory simply accepts the fact of such 

 a degree of stability appertaining to the substance of 

 heredity as the phenomena of atavism, &c. prove, 

 Weismann's theory postulates the stability of this 

 substance as absolute. But, as we have now so often 

 seen, he does so in order to provide a hypothetical 

 basis for his further theory of evolution. In as far as 

 his theory of heredity is concerned, there is no reason 

 why it should differ from Darwin's in this respect. 



Again, comparing Weismann's theory of heredity 

 with that of Galton, we found that germ-plasm 

 resembles stirp in all the points wherein we have just 

 seen that it resembles germ-plasm. Or, otherwise 

 stated, all three theories are thus far coincident. But 

 germ-plasm resembles stirp much more closely than 

 it does gemmules, seeing that the theory of stirp is 

 founded on the postulate of "continuity" in exactly 

 the same manner as is the theory of germ-plasm. In 

 point of fact, the only difference between these two 

 theories consists in the two further postulates presented 

 by the latter — viz., that the "continuity" in question 

 has been unbroken since the origin of life, while the 

 " stability " in question has been uninterrupted since 

 the origin of sexual propagation. But seeing that 

 both these additional postulates have reference to 

 Weismann s theory of evolution, we may say that his 



