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excrete. 1859 1860 1861 1866 1872
excrete I watched them for some time through a lens, but not one excreted; I then tickled and stroked them with a hair in the same manner, as well as I could, as the ants do with their antennæ; but not one excreted. 1869

1 blocks not present in 1859 1860; present in 1861 1866 1869 1872
It is certain, from the observations of Huber, that the aphides show no dislike to the ants: if the latter be not present, they are at last compelled to eject their excretion.

for the sole 1859 1860 1861 1866
solely for the 1869 1872

I do not believe 1859 1860
there is no evidence 1861 1866 1869 1872

in the world 1859 1860
OMIT 1861 1866 1869 1872

of a distinct 1859 1860 1861 1866
OMIT 1869 1872

in some few cases, 1859 1860 1861 1866
OMIT 1869 1872

have been here 1859
be here 1860 1861 1866 1869
be 1872

and prevented their attendance during several hours. After this interval, I felt sure that the aphides would want to excrete. I watched them for some time through a lens, but not one excreted; I then tickled and stroked them with a hair in the same
manner;
manner,
as well as I could, as the ants do with their antennæ; but not one excreted.
After- wards
Afterwards
I allowed an ant to visit them, and it immediately seemed, by its eager way of running about, to be well aware what a rich flock it had discovered; it then began to play with its antennæ on the abdomen first of one aphis and then of another; and
each,
each
aphis,
aphis,
as soon as it felt the antennæ, immediately lifted up its abdomen and excreted a limpid drop of sweet juice, which was eagerly devoured by the ant. Even the quite young aphides behaved in this manner, showing that the action was instinctive, and not the result of experience. But as the excretion is extremely viscid, it is
no doubt
probably
a convenience to the aphides to have it removed;
and
and
therefore probably
they
the
aphides
aphides
do not
instinctively
instinctively
excrete for the sole good of the ants. Although I do not believe that any animal in the world performs an action for the exclusive good of another of a distinct species, yet each
species
species
tries to take advantage of the instincts of others, as each takes advantage of the weaker bodily structure of
other species.
others.
So
again
again,
in some few cases, certain instincts cannot be considered as absolutely perfect; but as details on this and other such points are not indispensable, they may be here passed over.
As some degree of variation in instincts under a state of nature, and the inheritance of such variations, are indispensable for the action of natural selection, as many instances as possible ought to have been here given; but want of space prevents me. I can only
assert
assert,
that instincts certainly do vary— for instance,