658 PROCEEDINGS OF SECTION D. 
by sight.* Similar experiments were made by Plateau, who 
states that the artificial insects upon being moved about were 
pursued, and in some cases seized by the spiders, just as in the 
case of the true fly. ‘But these facts,” says Peckham, in com- 
bating Plateau’s assertion, ‘‘do not argue that their vision is 
very poor, since in nature they must be constantly meeting with 
new forms of life upon which they may prey. Spiders eat a great 
variety of things: caterpillars, beetles, bugs, ‘ walking-sticks,’ and 
in fact, all manner of insects, as well as other spiders.” T 
Now, in conducting experiments upon such subjects as the 
Athropoda, it is not only easy to make mistakes, but also to 
arrive at what appear to be hasty conclusions, because it is a 
difficult matter to decide upon a subject of which we can have 
little conception, and the sensations of these creatures is a case in 
point. This fact is clearly and logically demonstrated by Dr. and 
Mrs. Peckham} in their remarks upon the conclusions arrived at 
by MM. Plateau and Forel. The last-named authors experimented 
with several Citigrade spiders by separating them from their 
cocoons, “and having noted their difficulty in finding them again, 
concluded that their sight was very poor and short.” As a matter 
of fact these spiders, when so treated, do not rely upon, or even 
apply, the sense of sight when searching for their lost treasures. 
Those who have studied the habits of spiders know that the 
genus Lycosa carry their cocoons attached to the extremity of the 
abdomen, while those of the Dolomedes carry them with their 
falces. ‘‘It is indeed a well-established fact,” as the Peckhams 
say, “that when the cocoon is taken away from one of these 
spiders, she is very much disturbed by its loss, and searches eagerly 
about for it, and yet she may run all around it without finding it, 
never recognising it unless she comes very close. This is the 
truth, but not quite the whole truth. As a matter of fact she 
never recognises it unless she touches it ; but let her graze it ever 
so slightly with any part of her body and she instantly seizes it 
and reattaches it to her abdomen. 
“The action is so sudden and rapid that one may easily make the 
mistake of supposing that the spider, in coming very near, recog- 
nises the cocoon through the sense of sight, but close attention 
will prove that this is never the case. She always comes into 
actual contact with it before taking it. We feel very confident that 
when the spider loses the cocoon she never looks for it, but feels 
after it. This is not so strange as at first appears, for it is quite 
possible that the spider constructs the egg-sac, deposits her eggs 
in it, closes the aperture, and attaches it to her body without ever 
seeing it.”§ These remarks are followed by a record of a number 
*Trans. Wisconsin Acad. of Sci. Arts, and Letters, vol. x, p. 249. 
f Loc. cit., p. 236. t Loc. cit., p. 286. § Loc. cit., pp. 236, 237. 
