INTRODUCTION. 
'T HOSE animals which by their fize chiefly attraét our attention; 
are but the {mallet part of animated nature; the whole earth. 
fwarms with living beings, every plant, every grain and leaf; fupports 
the life of thoufands. Vegetables feem, at firlt figlit, to be the parts 
of organized nature, which are produced in the greateft abundance 5 
ut upon minuter infpe@ion we fhall find each fupporting numberlefs 
minute creatures, who fill up the vatiotis gradations of youth, vigours 
and old age, in the fpace of a few days exiftence. 
_ Vegetables are generally produced but once in a feafon; but among 
infects, efpecially of the fmaller kinds, a fingle fummer fuffices for fe- 
veral generations. ‘Thefe therefore. would multiply in greater abun-_ 
dance than the plants on which they fubfift; but that they are deftroy- 
éd by other animals, and often by each other; the fpider feeds on the 
fly, the birds upon the {piders, and they, in turn, make the food of 
man and every bealt of prey. ~ i! 
Some infeéts as to their conformation are compofed of feveral ringss 
joined together by a membrane, which is the ufual form of the body 
in grubs, worms, and caterpillars. Unlike birds, who traverfe the 
air with fuch rapidity, thefe humble animals, feemingly lefs favourites 
of nature, move forward but flowly. The whole body confifts of a 
chain of annular mufcles; whofe orbicular fibres being contracted, ren 
der one of the rings that was before ample and dilated narrow and long. 
‘The fibres of thefe rings are found to be fpiral; as are their motions in 
2 great meafure, fo that. by this means they can the better bore their 
_ Paflage into the earth. Their crawling motion may be explained by a 
Wire wound round a walking cane, which when flipt off, and attempt- 
ed to be lengthened; has an elaltie contraGion of one ring to the other. 
In like manner the earthworm, having fhot out or extended its bodys 
lays hold upon fome fubftance with its fmall feet, and fo brings onward. 
the hinder part of its body. : 
Caterpillars have feet both before and behind, which not only enable, 
them to move forward by a fort of fteps made by their fore and hinder 
parts, but alfo climb up vegetables, and to ftretch themfelves ont from 
the boughs and ftalks to reach food at a diftance. Behind, their broad. 
palms are befet almoft round with {harp {mall nails; to hold and grafp 
‘whatever theyfare upon; likewife before, their feet are harp and hook- . 
ed, by which they can lay hold of leaves, while their hinder parts are 
brought up thereto. Reptiles that have many feet may be obfefved to 
Move them regularly one after another; and from one end of the body 
to another, in fuch a manner that their legs in walking make a fort of 
undulation; and by this means they move much fwifter forward than 
one would imagine. The motion of fnails is performed in a different 
manner ; they have a broad fkin along each tide of the belly; which 
ed 
