188 Inheritance of Acquired Characters 
which there was equality and in which there were no 
castes, the neutrals being nothing else than females 
incompletely developed because of defective nutrition. 
It would not be correct to state that the question 
has been finally decided through this debate. While 
Weismann has not been able to prove conclusively that 
these harmonious modifications of the neutrals have been 
at least partially acquired after the development of castes 
and when the sterility of the neutrals had already 
appeared, neither has Spencer been able to demonstrate 
that all these harmonious modifications had been already 
acquired by the presocial ancestors. Nevertheless the 
conception of Spencer that the neutrals are produced by 
an arrest of development of the females has in our 
opinion won a decisive victory over that of his opponent, 
and has in reality taken from the last rampart of the 
Weismannists all the strength which it had derived from 
the conception that the neutrals were special formations, 
which had acquired special characters by fortuitous vari- 
ations and natural selection only. 
4. The fourth and last argument, that of the incon- 
ceivability of the transmission of acquired characters, has 
already been considered by Darwin in connection with 
examples which he had himself communicated of the 
inheritance of certain peculiarities, particularly of instincts 
acquired by domestic animals. “Nothing in the whole 
circuit of physiology,” he stated in this connection, “is 
more wonderful. How can the use or disuse of a partic- 
ular limb or of the brain affect a small aggregate of 
reproductive cells seated in a distant part of the body, 
in such a manner that the being developed from these 
cells inherits the characters of either one or both parents? 
