2^8 THE PHILOSOPHY 



chryfallds differ both in figure and colour, their appearances 

 are by no means fo various as thofe of the caterpillars from 

 which they are produced. The colour of fome chryfalids is 

 that of pure gold, from which circumflance the whole have 

 received their denomination. For the fame reafon they are 

 called aiirel'iae in Latin. Some are brown, others green *, and, 

 indeed, they are to be found of almoft every colour and 

 £hade. 



The life of winged infecSls confiffs of three principal pe- 

 riods, which prefent very different fcenes to the fludent of 

 Nature. In the flrft period, the infecl appears under the 

 form of a luor^n or caterpillar. Its body is long, cylindrical, 

 and confifts of a fucceffion of rings, which are generally 

 membranous, and encafed within each other. By the aid of 

 its rings, or of crotchets, or of feveral pairs of legs, it crawls 

 about in queft of food ; and its movements are, in fome fpe- 

 cles, remarkably quick. Its head is armed with teeth, or 

 pincers, by which it eats the leaves of plants or other kinds of 

 food. In this flate, it is abfolutely deprived of fex, and, con- 

 fequently, of the power of multiplication. Its blood moves 

 from the tail toward the head. It refpires either by ftigma- 

 ta or fmall apertures placed on each fide of its body, or by 

 one or feveral tubes fituated on its poflerior part, which have 

 the refemblance of fo many tails. In the fecond period, the 

 infe£l: appears under the form of a nymph, or that of a chry- 

 falis. When an infecSt, after throwing off the fkin of the 

 caterpillar, exhibits all its external parts, only covered with 

 foft and tranfparent membranes, it is called a nymph. But, 

 v^^hen to thefe membranes is added a common and cruftace* 

 ous covering, it receives the name of a chryfalis. While in 

 the ftate of a nymph, or that of a chryfalis, infe(Sls, in gener- 

 al, are totally inaflive, and feem not to pofTefs any powers of 

 life. Sunk into a kind of deep fleep, they are little affected 

 with external objeiTts. They can make no ufe of their eyes. 



