1 66 Evolution and Adaptation 



whose sole functions are those which Weismann's imagina- 

 tion bestows on them, are brought forward as though they 

 could supply the deficiencies of Darwin's theory. This is, 

 indeed, the old method of the philosophizers of nature. An 

 imaginary system has been invented which attempts to ex- 

 plain all difficulties, and if it fails, then new inventions are to 

 be thought of. Thus we see where the theory of the selection 

 of fluctuating germs has led one of the most widely known 

 disciples of the Darwinian theory. 



The worst feature of the situation is not so much that 

 Weismann has advanced new hypotheses unsupported by 

 experimental evidence, but that the speculation is of such a 

 kind that it is, from its very nature, unverifiable, and there- 

 fore useless. Weismann is mistaken when he assumes that 

 many zoologists object to his methods because they are 

 largely speculative. The real reason is that the speculation 

 is so often of a kind that cannot be tested by observation or 

 by experiment. 



