166 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. 
