392 
CLASS ARACHNiDA. 
struggle with it, the spider retires for a moment, to wait until 
the other has lost its strength, or become more entangled. 
But if there is nothing to fear, the spider hastens to fetter its 
prey, by winding its threads of silk round its body, which 
sometimes completely envelope it, and form a covering that 
withdraws it from our sight. 
Lister has asserted, that the spiders ejaculate and dart out 
their threads, in the same manner as the porcupines shoot 
their quills, with this difference, that the latter weapons, 
according to the popular opinion, are detached from the body, 
while in the spiders, these threads, though pushed to a dis- 
tance, remain attached to the animal. This feat has been 
considered impossible. Nevertheless, we have seen threads 
issuing from the nipples of some thomisi, directed in a right 
line, and forming, as it were, moveable radii, when the animal 
moved circularly. Another use of the silk, and common to all 
the female araneides,isin the construction of cocoons, destined 
to enclose their eggs. The contexture and the form of these 
cocoons are variously modified, according to the habits of 
the races : they are generally spheroidical. Some have the 
form of a cap, or that of a kettle ; some are supported on a 
pedicle or stem, or terminate in a knob. Foreign substances, 
such as earth, leaves, &c. sometimes cover them, at least 
partially. A finer tissue, a sort of wadding, or down, often 
envelopes the eggs internally : they are either free or agglu- 
tinated, and more or less numerous. These animals, being 
very voracious, the males, to avoid all surprise, and not to be 
the victims of a premature desire, approach their females at 
the season of love with the most extreme distrust and the 
greatest circumspection. The apparatus of generation in the 
males, or at all events that which is presumed to be so, is 
usually very complicated and various, formed of scaly pieces, 
more or less hooked and irregular, and of a white fleshy body, 
on which vessels are sometimes perceived, of a sanguine 
