1878.] The Senses of the Lower Animals. 307 
An experimentalist placed some caustic ammonia close to 
the head of a moth which was either asleep or “ shamming ” 
death, and was surprised to find that it took little or no 
notice of the pungent vapour. On the other hand, he ob- 
served that a loud and sudden sound seemed to startle the 
moth. To do the writer in question justice, he does not 
appear to have drawn from this single experiment the rash 
and sweeping conclusion that inserts are incapable of 
smelling. Others, however, were less cautious, and not a 
few paragraphs have appeared in consequence, in political 
and literary journals, to the effect that the supposed pos- 
session by inserts of a sense of smell must now be regarded 
as an exploded error. We have found, however, not indeed 
an insect, but a spider perfectly sensitive to the odour of 
ammonia. Being once annoyed out of all patience by a 
Tegenaria , which would persist in attaching her web to a 
burette-stand in the window of our laboratory, we unstop- 
pered a 20-oz. phial of the strongest ammonia, and presented 
it at her, in the hope of putting her to final rout. With the 
usual courage of her race she charged the strange object 
with so much eagerness as nearly to fall into the open bottle. 
Catching the fume, however, she at once turned tail, and 
fled precipitately. Perhaps if we fully understood the 
strudture of the olfadtory organs in moths we should see a 
reason why they are little affedted by a dose of ammonia 
from which we should shrink back half-stifled. Their nerves 
of smell do not appear to terminate in a mucous membrane 
liable to be irritated by ammonia. Furthermore, we have 
observed cases where odours repulsive to man appear indif- 
ferent, or even attractive, to insedts. That gnats possess 
the power of smell is demonstrated beyond all reach of 
doubt ; yet we have seen a crowd of these little beings 
dancing merrily over the ventilators of a shed from which 
the orange fumes of hyponitric acid were escaping in tor- 
rents. It would have been easy for them to have found an 
equally eligible place free from the pungent vapour, but 
they showed no disposition to withdraw. In summer 
mornings, also, we have frequently observed moths of 
various kinds drowned in bowls of solution of tin in aqua 
regia, whilst none of these nightly visitors had thought 
proper to commit suicide in a cistern of water close at hand. 
We were hence led to conclude that the odour of the tin 
solution was to them positively attractive. Such solutions 
indeed have, under certain circumstances, a faintly aromatic 
smell which might be likened to that of decaying fruit. 
But if insects thus — as we are warranted in concluding— 
x 2 
