i S7S.] The Senses of the Lower Animals. 305 
my coat and several times round the collar before I could 
place it in safety. I went from thence into my garden, to 
shut some hot-bed lights, where I was occupied about ten 
minutes ; from thence again to my study, where I found two 
fine males of Sphinx Convolvuli had, whilst in the garden, 
attached themselves to the collar of my coat, where the 
female had previously been.” This instance, we think, is 
absolutely decisive. A scent might be easily left adhering 
to the collar of the coat, whilst no one can conceive of a 
sound remaining. Male moths have further been known to 
flock to the empty cocoon from which a female had recently 
escaped, though she had in the meantime been removed. 
Sight and hearing being evidently thus out of the question, 
there remains only one sense known to us capable of adting 
at a distance. Judging from our own powers, indeed, scent 
of such delicacy and subtlety is simply incomprehensible. 
We wonder at the accuracy with which the harrier can track 
a hare, or the bloodhound a fugitive criminal or slave, over 
meadows, marshes, ploughed lands, and trodden roads ; and 
if common observation were not against us we should 
doubtless proclaim this also inconceivable or impossible. 
But the task of the hound is vastly easier than that of the 
moth. He is guided by scented surfaces to which the spe- 
cific odour of the animal pursued adheres in a concentrated 
form. The emanations from the female moth, on the other 
hand, are diffused through space and diluted with an ex- 
cessive quantity of air, whether scentless or saturated with 
other odours. Yet this infinitesimal trace is sufficient to 
guide the male towards her with unfailing accuracy, and 
from distances of at least 200 yards, or about 3600 times 
the length of the insedt’s body. This is as if a human being 
were able to detedt the presence and the condition of an 
individual of his own species at the distance of more than 
four miles ! Inconceivable, however, as such a power may 
seem to us, there stand the fadts before us, and we have 
merely the option of admitting this wonderful delicacy of 
scent or assuming the existence of some sense totally foreign 
to us, and possessed of equal delicacy in its indications. 
According to the observations of Mr. Belt,* confirmed by 
those of others, the Ecitons and other ants follow each other 
by scent. Each exploring party marks out thus the road it 
has travelled. He says : — “ I one day saw a column of 
Eciton hamata running along the foot of a nearly perpendi- 
cular tramway-cutting, the side of which was about 6 feet 
* Naturalist in Nicaragua, p. 23. 
yok ? yin, (n.s.) 
x 
