82 An Examination of Weismanmsm. 



mitted to progeny by the more ordinary methods of 

 sexual propagation (Lamarckian factors). This second 

 line of evidence will be fully and independently dealt 

 with in future chapters, specially devoted to the 

 subject. Therefore we have here to consider only the 

 first. 



Now, the force of this first line of evidence will 

 become apparent if we reflect that the only way 

 iti which the facts can be met by Weismann's theory, 

 would be by supposing that the somatic germ-plasms 

 which are respectively diffused through the cellular 

 tissues of the scion and the graft become mixed in 

 some such way as they might have been, had the 

 hybrid been due to seminal propagation instead of to 

 simple grafting. But against this, the only interpre- 

 tation of the facts which is open to the theory, there 

 lies the following objection, which to me appears 

 insuperable. 



Where sexual cells are concerned there is always 

 a definite arrangement to secure penetration of the 

 one by the other, and we can see the necessity for 

 such an arrangement in order to effect an admixture of 

 their nuclear contents, where alone germ-plasm is 

 supposed by Weismann's theory to reside. But in 

 tissue-cells which have not been thus specialized, it 

 would be difficult to believe that nuclear contents can 

 admit of being intimately fused by a mere apposition 

 of cell-walls. For not only are the nuclear contents of 

 any two such cells thus separated from one another 

 by two cell-walls and two masses of " cytoplasm " ; 

 but it is not enough to suppose that in order to 

 produce a graft-hybrid only two of these somatic-cells 

 need mix their nuclear contents as we know is all 



