1897. COPE'S ''FACTORS OF EVOLUTION:' 45 



the facts around us necessitates another explanation behind it, and so, 

 if modifications are inherited, the biologist has to explain how they 

 are inherited. This is why Weismann appealed to us : not because he 

 explained evolution, for Darwin, Wallace, and Spencer had done that, 

 but because he explained their explanation, showing how it worked 

 through the known mechanics of reproduction and cell-division. Now 

 the explanation of evolution by Lamarck is not opposed to the 

 explanation by Darwin, it is complementary to it. What it is opposed 

 to is the germ-plasm theory, at all events as first strictly stated by 

 Weismann. Professor Cope, therefore, who follows Lamarck, is 

 obhged to provide some explanation of the way in which a modification 

 of the adult soma is transmitted to the already differentiated germ- 

 plasm. His first step is to propound what he calls the Theory of 

 Diplogenesis. This supposes that a cause affecting the soma actually, 

 likewise affects the germ-plasm, but affects it potentially. It is hard 

 for us to understand how an external cause influences the soma, but 

 we know that it does so ; it is hard for us to understand how the germ 

 grows into the adult with the characters of the parent, but we know 

 that it does so ; is it any harder for us to understand how the same 

 external cause may influence the germ while yet within the parent ? 



Professor Cope, it is true, does not present us with a wonderful 

 mechanism of speculative ids, idants, and the rest, linked to a set 

 of physical appearances upon which no two cytologists are agreed, 

 and so we must admit that his explanation, even if it be accepted, 

 requires some further explanation. But, so far as this goes, his 

 theory is no worse than anyone else's, and it seems safer to wait 

 for the principles of cellular biology to settle before applying 

 them to these speculative questions. Rejecting all hypotheses basedi 

 on pangenetic principles, i.e. on the transference of material' 

 character-beariug particles, Professor Cope relies on the action 

 of a growth-force, to which he gives the name " bathmism." This 

 in its turn requires explanation, and .it is explained as the action 

 of a kind of unconscious memory, with which faculty the repro- 

 ductive cells are endued. Impressions are transmitted to these 

 cells through the continuous protoplasm of the organism, and 

 the cells retain, " first the impressions received during their 

 primitive unicellular ancestral condition, and second, those which 

 ihey have acquired through the organism of which they have 

 been and are only a part." When we are able to give a physical 

 explanation of conscious memory, it will be time enough to consider 

 this heredity theory of Professor Cope, or rather of Hering. At 

 present, like many other fascinating speculations, it is as incapable of 

 proof as of disproof. 



The final section of Chapter VIII. recapitulates some of the 

 objections that have been raised to the doctrine of the inheritance of 

 modifications. This, however, chiefly discusses special cases, with 

 which the theory neither stands nor falls. 



