CH I.] METAMORPHOSES OF INSECTS. 21 



from the pupa. The shade of colour in these gilded 

 chrysalides is various : some are of a rich yellow, 

 like pure gold, others much paler, and some nearly 

 as white as siiver." 



Respecting the gradual manner in which the va- 

 rious limbs of a butterfly are developed in the milky 

 fluid with which the body of a newly-disclosed 

 chrysalis is filled, and in which the rudiments of its 

 future limbs and organs, themselves almost as fluid, 

 swim, it does not appear that sufficiently precise 

 experiments have hitherto been made. It was the 

 opinion of Swammerdam, who dissected chrysalides 

 at the end of two, six or eight, twelve or thirteen, 

 and sixteen or seventeen days, after they had as- 

 sumed that form, that it was by evaporation of the 

 superfluous humidity, or by the help of an insensible 

 perspiration, that the enclosed limbs of a butterfly 

 acquire their full strength. 



Reaumur, who investigated the subject with 

 greater nicety than any other naturalist, observes, 

 " a chrysalis remains many weeks, and often many 

 months, without taking any sustenance, and during 

 so long a fast, some evaporation must assuredly 

 take place ; but to what a shadow would its body be 

 consequently reduced if the greatest part of the 

 liquor which penetrates its diflferent parts were to 

 evaporate. It appears to me more probable, that 

 this fluid unites or is incorporated with the more 

 solid parts of the chrysalis, and that it becomes 

 thicker when thus united, giving greater solidity to 

 the different parts, in the same manner as the blood 

 and lymph are employed to effect the same purpose 

 in our own bodies ; and the fluid which nourishes 

 the limbs of a chrysalis surrounds, or, as it were, 

 bathes them individually, so that the envelope of 

 each of these parts being chiefly employed to pre- 

 vent too much evaporation, may be regarded as per- 

 forming an office analogous to that of the shell of 

 me egg." 



