228 



Microscopical Essays, 



alfo from the eyes, and no more perform their office. The muf- 

 cles of the rings alfo in like manner, and a great part of the pul- 

 monary points of refpiration, are feparated from, the external 

 fkin. Thus the whole body contracts itfelf by degrees into a 

 fmall compact mafs. At this time the gullet and the pulmonary 

 tubes caft a coat within the fkin. To make this evident, it is 

 neceffary to open the abdomen, when the pupa, it's parts, to - 

 gether with the caft off pulmonary pipes, may be clearly feen. 



An exact account of all the changes of the interior parts is to 

 be found in Swammerdam's Book of Nature. Thefe changes are 

 beft examined by taking the pupa out of the fkin, or outfide cafe, 

 when it begins to harden ; for as it has not then quite attained the 

 pupa form, and the members are fomewhat different from what 

 they will be when in that ftate, it is more eafy to obferve their 

 refpective fituation, than when the pupa is fome days older, and 

 has loft the greateft part of the fuperfluous humours. The pupa 

 is inclofed in a double garment ; the interior one is a thin mem- 

 brane, which invefts it very clofely • the other, or exterior one, 

 is formed of the outermoft hard (kin of the larva, within which it 

 performs it's changes in an invifible manner : it is this fkin which 

 gives it the appearance of the larva while in the pupa ftate. 



When the time .approaches that the hidden infect, now in the 

 pupa form within it's old covering, is to attain the imago, fly, or 

 perfect ftate, which generally happens in about eleven days after 

 the preceding change, the fuperfluous humours are evaporated by 

 infenfible perfpiration. The little pupa is contracted unto the 

 fifth ring of the fkin, and the four laft rings of the abdomen are 

 filled with air, through the aperture in the refpiratory orifice of 



the 



