XIV 
FUNDAMENTAL PROBLEMS 
417 
of the existence of animals in a state of domestication, we 
should expect to find that, in wild species, all unused parts or 
organs had been reduced to the smallest rudiments, or had 
wholly disappeared. Instead of this we find various grades 
of reduction, indicating the probable result of several distinct 
causes, sometimes acting separately, sometimes in combination, 
such as those we have already pointed out. 
And if we find no positive evidence of disuse, acting by its 
direct effect on the individual, being transmitted to the offspring, 
still less can we find such evidence in the case of the use of 
organs. For here the very fact of use, in a wild state, implies 
utility, and utility is the constant subject for the action of 
natural selection ; while among domestic animals those parts 
which are exceptionally used are so used in the service of man, 
and have thus become the subjects of artificial selection. 
Thus “ the great and inherited development of the udders in 
cows and goats,” quoted by Spencer from Darwin, really affords 
no proof of inheritance of the increase due to use, because, 
from the earliest period of the domestication of these animals, 
abundant milk-production has been highly esteemed, and has 
thus been the subject of selection ; while there are no cases 
among wild animals that may not be better explained by 
variation and natural selection. 
Difficulty as to Co-adaptation of Parts by Variation and Selection. 
Mr. Spencer again brings forward this difficulty, as he 
did in his Principles of Biology twenty-five years ago, and 
urges that all the adjustments of bones, muscles, blood-vessels, 
and nerves which would be required during, for example, the 
development of the neck and fore-limbs of the giraffe, could 
responding congenital diminution of the unused organ ; and in cases where 
the means of nutrition are deficient, every diminution of these useless parts 
will he a gain to the whole organism, and thus their complete disappearance 
will, in some cases, he brought about directly by natural selection. This 
corresponds with what we know of these rudimentary organs. 
It must, however, be pointed out that the non-heredity of acquired char¬ 
acters was maintained by Mr. Francis Galton more than twelve years ago, on 
theoretical considerations almost identical with those urged by Professor Weis- 
inann ; while the insufficiency of the evidence for their hereditary trans¬ 
mission was shown, by similar arguments to those used above and in the work 
of Professor Weismann already referred to (see “A Theory of Heredity,” in 
Journ. Anthroj). Instit., vol. v. pp. 343-345). 
