lejndopterous larvce and pupce. 179 



the gain due to oxidation of the pupal surface, and this 

 could be confirmed by investigating whether the darkening 

 and hardening and the weight of the flask is affected (in 

 the case of another pupa) by drawing through some 

 harmless gas, such as nitrogen or hydrogen, instead^ of 

 air. I hope to perform such experiments in the coming 

 season. 



The experiments above recorded are not intended to 

 indicate the normal loss of weight in pups throughout 

 the quiescent period, although it was necessary, for the 

 purpose of comparison, to obtain an approximate average 

 of the rate of normal loss in the species investigated. 

 The normal loss throughout the period (omitting the 

 immense early loss which it has been my object to 

 demonstrate and measure) has been thoroughly investi- 

 gated by Professor Meldola, and compared with the 

 greater loss in a dead pupa (Ann. and Mag. Nat. Hist., 

 Oct., 1873). 



