330 Difficulties of Darwinism. [July, 
situation may afford, those points of transit must have ren- 
dered fecundation more dangerous and less easy. We 
should therefore expect that the line of descent in which 
these variations were occurring would—in the ordinary 
working of Natural Selection—tend to become extin&. 
The distribution in the animal kingdom of the power of 
secreting poisons requires, also, much additional light. We 
may distinguish here two stages :—In the lower, poisonous 
fluids are indeed elaborated, or some of the solids of the 
body possess venomous properties, but the animal has no 
special apparatus for injecting them into the tissue of an 
enemy or of a victim. In the higher, there exist—in addi- 
tion to the secreting glands and the receptacles for the 
poison—either hollow fangs, or stings, or some analogous 
weapon. In neither of these forms does the poison-faculty 
occur among Mammalia and birds, at least in a normal, 
healthy condition.* Among reptiles it seems restricted to 
one particular group, the Ophidians, where it receives its 
maximum development. Why, then, has no similar power 
been evolved among warm-blooded animals and among non- 
ophidian reptiles? Why, again, is the venom of serpents 
much more intense than is required for the destruction of 
their prey? The cobra feeds chiefly upon rats, but its bite 
is amply sufficient to cause the death of a man, a swine, or 
a sheep, which it is utterly unable to swallow. Nor, after 
all, can the venom of snakes be of great value to them for 
defensive purposes, since the bite of few species, if of any, 
is sufficiently rapid to prevent the bitten animal taking 
instant revenge. As, therefore, increased activity of venom 
can have conferred little especial advantage upon its pos- 
sessors, either in procuring food or for the purpose of self- 
defence, it is difficult to see how its development can have 
been effected on the principle of Natural Selection. Still 
less can we conceive of it as due to Sexual Selection. The 
power, possessed as it is by both sexes, does not appear cal- 
culated to render either more attractive to the other. 
Passing over the fishes, in some of which the venom- 
faculty exists in its higher stage of development, we come 
to the Articulata. Here true venoms exist in the Hymen- 
optera, Heteroptera, probably in certain Diptera, as well as 
in many spiders, scorpions, and centipedes.f On the other 
* Is hydrophobia, as occurring among wild Canidz, such as wolves and 
jackals, invariably fatal? Its extreme frequency among those species leads 
us to doubt whether such is the case. 
+ The bite of the common English centipede, as the writer can testify, is 
more painful than the sting of a wasp. 
