Microscopical Essays, 237 



their reparation ; this moiflure evaporates by degrees, all the 

 parts acquire a confidence, and the infect, is then in a condition, 

 to aft. 



The firft ufe that feme caterpillars, who live on leaves, make 

 of their new form, is to devour greedily their exuvia ; fometimes 

 they do not wait till their jaws have acquired their full ftrength ; 

 fome have been feen to gnaw the {hell from which they pro- 

 ceeded, and even the eggs of fuch caterpillars as have not been 

 hatched. 



When we have once formed the idea that all the exterior parts 

 are inlaid, or included one within the other, the production of 

 new organs does not appear fo embarraffing, being nothing more 

 than a fimple developement ; but it is more difficult to 

 form any conception of the changes that happen in the vifcera 

 before and after the transformation, the various modifications, 

 they undergo eluding our refearches. We have already obferved, 

 that a little before the change the caterpillar rejecls the membrane 

 that lines the mteftinal bag : this bowel has hitherto di gelled 

 only grofs food, whereas it muff hereafter digeft that which is 

 very delicate : a fluid that circulates in the caterpillar, from the 

 hind part towards the head, circulates a contrary way after trans- 

 formation. Now if this inverfion is as real as obfervation leems, 

 to indicate, how amazing the change the interior parts of the ani- 

 mal muft have undergone ! When the caterpillar moults, imail 

 clutters of trje tracheal veffels are call: off with the exuvia, and 

 new ones are fubftituted in their room 3 but how is this effected, 

 how are the lungs replaced by other lungs ? The more we 



endeavour 



