from the eggs deposited in the plant by the insect.
Now, without question, this is a most remarkable fact; and if there were
many more of the like kind to be met with in organic nature, we might
seriously consider whether the formation of galls should not be held to
make against the ubiquitous agency of natural selection. But inasmuch as
the formation of galls stands out as an exception to the otherwise
universal rule of every species for itself, and for itself alone, we are
justified in regarding this one apparent exception with extreme
suspicion. Indeed, I think we are justified in regarding the peculiar
pathological effect produced in the plant by the secretions of the
insect as having been in the first instance accidentally beneficial to
the insects. Thus, if any other effect than that of a growing tumour had
been produced in the first instance, or if the needs of the insect
progeny had not been such as to have derived profit from being enclosed
in such a tumour, then, of course, the inoculating instinct of these
animals could not have been developed by natural selection. But, given
these two conditions, and it appears to me there is nothing very much
more remarkable about an accidental correlation between the effects of a
parasitic larva on a plant and the needs of that parasite, than there is
between the similarly accidental correlation between a hydated parasite
and the nutrition furnished to it by the tissues of a warm-blooded
animal. Doubtless the case of galls is somewhat more remarkable,
inasmuch as the morbid growth of the plant has more concern in the
correlation--being, in many instances, a more specialized structure on
the part of a host than occurs anywhere else, either in the animal or
vegetable world. But here I may suggest that although natural selection
cannot have acted upon the plant directly, so as to have produced galls
ever better and better adapted to the needs of the insect, it may have
so acted upon the plants indirectly _though the insects_. For it may
very well have been that natural selection would ever tend to preserve
those individual insects, the quality of whose emanations tended to
produce the form of galls best suited to nourish the insect progeny; and
thus the character of these pathological growths may have become ever
better and better adapted to the needs of the insects. Lastly, looking
to the enormous number of relations and inter-relations between all
organic species, it is scar