190 
OF INSECTS. 
and, if one might so speak concerning the works of nature, 
an original contrivance. Other animals have their proper 
retreats, their hybernacula also, or winter-quarters, but the 
snail carries these about with him. He travels with his 
tent; and this tent, though, as was necessary, both light 
and thin, is completely impervious either to moisture or air. 
The young snail comes out of its egg with the shell upon 
its back; and the gradual enlargement which the shell 
receives, is derived from the slime excreted by the animal’s 
skin. Now the aptness of this excretion to the purpose, its 
property of hardening into a shell, and the action, whatever 
it be, of the animal, whereby it avails itself of its gift, and 
of the constitution of its glands, (to say nothing of the work 
being commenced before the animal is born,) are things 
which can, with no probability, be referred to any other 
cause than to express design; and that not on the part of 
the animal alone, in which design, though it might build 
the house, could not have supplied the material. The will 
of the animal could not determine the quality of the ex¬ 
cretion. Add to which, that the shell of a snail, with its 
pillar and convolution, is a very artificial fabric; whilst a 
snail, as it should seem, is the most numb and unprovided 
of all artificers. In the midst of variety, there is likewise 
a regularity, which would hardly be expected. In the 
same species of snail, the number of turns is usually, if 
not always, the same. The sealing up of the mouth of 
the shell by the snail, is also well calculated for its warmth 
and security; but the cerate is not of the same substance 
with the shell. 
II. Much of what has been observed of snails belongs 
to shell-Jish and their shells, particularly to those of the 
univalve kind; with the addition of two remarks: one of 
which is upon the great strength and hardness of most of 
these shells. I do not know whether, the weight being 
given, art can produce so strong a case as are some of these 
shells. Which defensive strength suits well with the life 
of an animal, that has often to sustain the dangers of a 
stormy element, and a rocky bottom, as well as the attacks 
of voracious fish. The other remark is, upon the property, 
in the animal excretion, not only of congealing, but of con¬ 
gealing, or, as a builder would call it, setting, in water, and 
into a cretaceous substance, firm and hard. This property 
is much more extraordinary, and, chemically speaking, 
more specific, than that of hardening in the air; which 
may be reckoned a kind of exsiccation, like the drying oi 
clay into bricks. 
