964 DIVISION II. ARTICULATED ANIMALS.—CLASS TI. ARACHNIDA. 
spider, the latter retires for a time, until it has lost its strength, and be- 
comes still more entangled in its ineffectual efforts to escape, when, there 
being no longer cause for alarm, the spider returns, and endeavors to twirl 
it round, weaving at the same time around it a strong, silken web, in which 
it is sometimes entirely encased. Lister states that the spiders discharge 
their threads in the same manner as the porcupine is fabulously asserted to 
do, with this difference — that the threads of the spider remain attached to 
its body. This fact has been considered impossible. We have, however, 
seen the threads issue from the nipples of some Thornisi, extending in a 
straight line, and forming movable rays when the animal moves them circu- 
larly. Another use of silk common to all female spiders is for the con- 
struction of cocoons destined for the enclosure of the eges. The contexture 
and the form of these cocoons are varied according to the habits of the vari- 
ous races of spiders. They are generally spheroid; some have the shape 
of a cap or a flat sphere; some are placed on a peduncle, and others are 
terminated by a club. Other matters, such as earth, leaves, &c., sometimes 
cover them, or at least partially ; a finer tissue often envelops the eggs in 
the inside, where they are loose or agglutinated together, and are more or 
less numerous. 
The spider's web is undoubtedly one of the most curious and extraor- 
dinary objects in nature. Most wonderful is the tenuity of these fairy-like 
lines, yet strong enough to enable the aerial voyager to run through the air, 
and catch his prey which ventures within its domain. It is so fine that, 
in the web of the Gossamer Spider, the smallest of the tribe, there are 
twenty tubes, through which are drawn the viscid globules, the gummy mat- 
ter it employs in spinning. It takes one hundred and forty of these 
globules to form a single spiral line: it has twenty-four circumlocutions to 
go through, which gives the number of three thousand three hundred and 
sixty. We have thus got the average total number of lines between two 
radii of the circle; multiplying that number by twenty-six, the number of 
radii which the untiring insect spins, gives the total amount of eighty-seven 
thousand three hundred and sixty viscid globules before the net is com- 
plete. 
The dimensions of the net, of course, vary with the species. Some will 
be composed of as many as one hundred and twenty thousand lines; yet 
even to form this net, the spider will only take five minutes! Wonderful, 
indeed, is the process by which the spider draws the thread from its body — 
more wonderful than any rope or silk-spinning. Each of these spinnerets 
is covered with rows of bristle-like points, so very fine that a space about 
the size of a pin’s head will cover a thousand of them. From each of these 
points or tubes issues a small but slender thread, which unites with the other 
