ase of neuter insects all of one caste, which, as I believe, have been
rendered different from the fertile males and females through natural
selection, we may conclude from the analogy of ordinary variations, that
the successive, slight, profitable modifications did not first arise in
all the neuters in the same nest, but in some few alone; and that by
the survival of the communities with females which produced most neuters
having the advantageous modification, all the neuters ultimately came to
be thus characterized. According to this view we ought occasionally
to find in the same nest neuter-insects, presenting gradations of
structure; and this we do find, even not rarely, considering how few
neuter-insects out of Europe have been carefully examined. Mr. F. Smith
has shown that the neuters of several British ants differ surprisingly
from each other in size and sometimes in colour; and that the extreme
forms can be linked together by individuals taken out of the same nest:
I have myself compared perfect gradations of this kind. It sometimes
happens that the larger or the smaller sized workers are the most
numerous; or that both large and small are numerous, while those of an
intermediate size are scanty in numbers. Formica flava has larger
and smaller workers, with some few of intermediate size; and, in this
species, as Mr. F. Smith has observed, the larger workers have simple
eyes (ocelli), which, though small, can be plainly distinguished,
whereas the smaller workers have their ocelli rudimentary. Having
carefully dissected several specimens of these workers, I can affirm
that the eyes are far more rudimentary in the smaller workers than can
be accounted for merely by their proportionately lesser size; and I
fully believe, though I dare not assert so positively, that the workers
of intermediate size have their ocelli in an exactly intermediate
condition. So that here we have two bodies of sterile workers in the
same nest, differing not only in size, but in their organs of vision,
yet connected by some few members in an intermediate condition. I may
digress by adding, that if the smaller workers had been the most useful
to the community, and those males and females had been continually
selected, which produced more and more of the smaller workers, until all
the workers were in this condition; we should then have had a species of
ant with neuters in nearly the same condition as those of Myrmica. For
the workers of Myrmic