VI 
DIFFICULTIES AND OBJECTIONS 
139 
which are not rudiments of once useful organs, we cannot see 
what there is to ensure any amount of constancy or stability. 
One of the cases on which Mr. Romanes lays great stress in 
his paper on “Physiological Selection” ( Journ. Linn.Soc., vol. xix. 
}). 384) is that of the fleshy appendages on the corners of the 
jaw of Normandy pigs and of some other breeds. But it is 
expressly stated that they are not constant; they appear 
“ frequently,” or “ occasionally,” they are “ not strictly 
inherited, for they occur or fail in animals of the same litter 
and they are not always symmetrical, sometimes appearing 
on one side of the face alone. Now whatever may be the 
cause or explanation of these anomalous appendages they 
cannot be classed with “specific characters,” the most 
essential features of which are, that they are symmetrical, 
of growth. But, when so reduced, the rudiment might he inconvenient or even 
hurtful, and then natural selection would aid in its complete abortion ; in 
other words, the abortion of the part would be useful , and would therefore be 
subject to the law of survival of the fittest. The genera Ateles and Colobus 
are two of the most purely arboreal types of monkeys, and it is not difficult 
to conceive that the constant use of the elongated fingers for climbing from 
tree to tree, and catching on to branches while making great leaps, might 
require all the nervous energy and muscular growth to be directed to the 
fingers, the small thumb remaining useless. The case of the Potto is more 
difficult, both because it is, presumably, a more ancient type, and its actual life- 
history and habits are completely unknown. These cases are, therefore, not 
at all to the point as proving that positive specific characters—not mere 
rudiments characterising whole genera—are in any case useless. 
Mr. Mivart further objects to the alleged rigidity of the action of natural 
selection, because wounded or malformed animals have been found which had 
evidently lived a considerable time in their imperfect condition. But this 
simply proves that they were living under a temporarily favourable environ¬ 
ment, and that the real struggle for existence, in their case, had not yet 
taken place. We must surely admit that, when the pinch came, and when 
perfectly formed stoats were dying for want of food, the one-footed animal, 
referred to by Mr. Mivart, would be among the first to succumb; and the 
same remark will apply to his abnormally toothed hares and rheumatic 
monkeys, which might, nevertheless, get on very well under favourable 
conditions. The struggle for existence, under which all animals and plants 
have been developed, is intermittent, and exceedingly irregidar in its incidence 
and severity. It is most severe and fatal to the young ; but when an animal 
has once reached maturity, and especially when it has gained experience by 
several years of an eventful existence, it may be able to maintain itself under 
conditions which would be fatal to a young and inexperienced creature of the 
same species. The examples adduced by Mr. Mivart do not, therefore, in 
any way impugn the hardness of nature as a taskmaster, or the extreme 
severity of the recurring struggle for existence. 1 
1 See Nature, vol. xxxix. p. 127. 
