Darwin's Artificial and Natural Selection 165 
for my part, have never assumed this, and have on this very 
account enunciated the principle of panmixia. Now, although 
this, as I have still no reason for doubting, is a perfectly cor- 
rect principle, which really does have an essential and indis- 
pensable share in the process of retrogression, still it is not 
alone sufficient for a full explanation of the phenomena. 
My opponents, in advancing this objection, were right, to the 
extent indicated, and as I expressly acknowledge, although 
they were unable to substitute anything positive in its stead 
or to render my explanation complete. The very fact of the 
cessation of control over the organ is sufficient to explain its 
degeneration, that is, its deterioration, the disharmony of its 
parts, but not the fact which actually and always occurs 
where an organ has become useless — viz., z¢s gradual and 
unceasing diminution continuing for thousands ana thousands 
of years and culminating in its final and absolute effacement.” 
If then neither selection of persons nor the cessation of 
personal selection can explain the phenomenon, we must 
look elsewhere for the answer. This Weismann finds in 
the application of Roux’s hypothesis of the struggle of the 
parts to obtain nourishment. 
“The production of the long tail-feathers of the Japanese 
cock does not repose solely on the displacement directly 
effected by personal selection, of the zero point of variation 
upward, but that zt zs also fostered and strengthened by 
germinal selection. Were that not so, the phenomena of the 
transmutation of species, in so far as fresh growth and the 
enlargement and complication of organs already present are 
concerned, would not be a whit more intelligible than they 
were before.” 
Thus Weismann has piled up one hypothesis on another as 
though he could save the integrity of the theory of natural 
selection by adding new speculative matter to it. The most 
unfortunate feature is that the new speculation is skilfully 
removed from the field of verification, and invisible germs 
