308 IXSECT TRANSFORM ATIOIN'S. 



a few weeks, at another several months in that 

 state."* 



But though we admit all these facts, which are 

 known to every naturalist, and too well ascertained 

 to be denied, we submit that the inference of evapo- 

 ration being the exclusive effect, is, upon the whole, 

 inadmissible. Reaumur, though he does not abso- 

 lutely state his belief in such an inference, shows by 

 his reasoning that he was strongly disposed to adopt 

 notions closely Iwrdering upon it. The theoretical 

 doctrnie, it may be perceived, takes for granted that 

 evaporation is the only result of heat; overlooking 

 the no less obvious effect of expansion, besides 

 the disposition it produces in chemical principles to 

 combine or be decomposed. But these are only 

 some of its inanimate results, which would occur 

 upon material objects independently of life; whereas 

 in living bodies, what maybe called chemical changes 

 are frequently very different from what can be effected 

 out of the living body, and consequently we cannot 

 trace all the effects produced by heat in the two great 

 internal processes of secretion and consolidation. 

 In detailing, therefore, the interesting experiments 

 of Reaumur on pupae, which he subjected to different 

 degrees of heat and cold, we shall not adopt his in- 

 fer^;nces respecting evaporation. The accuracy of 

 the experiments themselves is unquestionable. 



Reasoning from some of the facts above stated, 

 Reaumur thought it might be possible to hasten or 

 retard the exclusion of insects from their pupje, in 

 the same way as some flowers are forced to blow 

 early, and others kept back from blowing at their due 

 season ; and he commenced a series of experiments to 

 ascertain the facts. In January, 1734, he accordingly 

 placed a great number of the chrysalides of moths 

 and butterflies of various species in one of the royal 

 * Iiitr. iii. 263. 



