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immense numbers of very minute ones jointed throughout their length, 
and readily separating into barbs sharply pointed at one end and 
trifid at the other. These hairs parted from the caterpillar so readily 
that persons looking at them, while they were feeding, had felt annoy- 
ance, as though the mere movement of the caterpillar separated the 
hairs, which, like those of the processionary moth, were wafted by the 
wind. Some very peculiar hairs were found on the vapourer, knobbed 
and plumed at the end ; a similar, but more extensive, knob was seen 
on the hairs of a South American caterpillar. The hairs on the 
tortoiseshell and other Vanessidz were very stout and jointed, while 
those from the white-plume moth caterpillar were imbricated and had 
somewhat the appearance of wool. Sufficient had been said to show 
there was such variety and beauty among caterpillar hairs as to 
recommend them to the notice of microscopists, who had simply 
studied, as far as he could gather, those from the larve of Dermestes 
and the pencil tail, which were well known as test objects of great beauty. 
A question might arise—Whence the urticating power? In the 
hair alone, or some irritating substance within the hair? He inclined 
to the former, because hairs from cast skins kept for years, and from 
cocoons two or three years old, were equally urticating with those 
from a living caterpillar, as were also the hairs mingled with the webs 
spun by some of the sociable larve. He looked upon it as a merely 
mechanical action, similar to that produced by the hairs of the 
prickly pear, those from the interior of the fruit of the wild rose or 
Cowage, Dolichos urens, all of which were equally productive of 
irritation, inflammation, and feverishness. 
To make out their structure caterpillar hairs should be mounted 
dry, in fluid and in balsam, Anyone turning his attention to them and 
not minding the risk of an occasional annoyance would be well re- 
warded for his fazus, and possibly wonder why more attention had not 
been paid by microscopists to so interesting and instructive a class of 
objects. He could only account for the apparent neglect on the ground 
that few entomologists worked with the microscope, and that micro- 
scopists generally had thought the hairs of all caterpillars alike, 
whereas, as with the scales of the lepidoptera, so with the hairs of their 
larvee, there was great variety of form and markings. 
Finding so little said about them, and having, moreover, worked 
at them for some years, he considered the subject of sufficient interest 
