298 INSECT TRANSFORMATIONS. 



they, " soon after its assumption of that state, you 

 will find its interior filled with a milky fluid, in the 

 midst of which the rudiments of its future limbs and 

 organs, themselves almost as fluid, swim. Now the 

 end to be accomplished during the pupa's existence 

 is, the gradual evaporation of the watery parts of this 

 fluid, and the development of the organs of the en- 

 closed animal by the absorption and assimilation of 

 the residuum."* The evaporation, however, is so 

 very inconsiderable, that it is evidently only of se- 

 condary consequence. 



When the great quantity of fluid in the body of the 

 chrysalis is taken into consideration, we must infer 

 that if it were evaporated to any extent, the insect 

 would be reduced to a mere shadow. We are dis- 

 posed, therefore, to agree with Reaumur in thinking 

 it more probable that the fluids of pupae become 

 united to the more solid parts, in the same way as 

 the blood and lymph in our own bodies go to the ex- 

 tension or to the repair of our bones and muscles. 

 To put this to the test of experiment, R(5auraur, in the 

 month of July, accurately weighed two chrysalides 

 the instant they were disencumbered of the sloughs 

 of the larvae. The lightest weighed a trifle less than 

 18, and the heavier a trifle less than 19 grains. 

 Putting them aside separately, with a note of their 

 respective weights, he re-weighed them every two or 

 three days for sixteen days successively, that is, till 

 they were transformed into perfect insects. On the 

 last day, the lighter weighed more than 17, and the 

 heavier more than 18 grains; consequently the fluid 

 evaporated during this period did not amount to a 

 grain, perhaps not more than J of a grain. On 

 weighing the insects themselves which issued from 

 these pupa, together with the cast slough, the weight 

 was not sensibly different. The fluid, therefore, 



* Introd. iii. 262 



