364 Vernon L. Kellogg and R. G. Bell. 



The twentieth larv^a of the lot was to be deprived of food 216 

 hours after the fourth moult, but it began spinning up in 200 

 hours (eight days) after, and pupated on the following day. Here 

 is a normal variation of four days out of the usual twelve of the 

 last feeding stage, just about as much shortening as the extreme 

 that could be induced by actual deprivation of food. 



Loss of Weight Daring Pupal Life. 



A belief among commercial breeders of silkworms that there 

 is a loss in weight of the cocoons (silk) accompanying pupal life 

 is indicated by their recognized wish to make an early sale of the 

 cocoon product. This loss is generally attributed to "evaporation 

 from the cocoon." The question arose as to whether the loss in 

 weight of the pupa-containing cocoon might be not a loss in weight 

 of silk but an accompaniment of developmental changes in the 

 pupa, a process in which stores of nourishment (in the larval body) 

 are being converted into moth with chemical changes which might 

 occasion some loss in weight. Therefore in four individuals the 

 cocoon and pupa were weighed separately once each day from the 

 time of pupation to time of emergence of the moth, while at the 

 same time the daily weights of the naked chrysalids of three other 

 lepidopterous species were determined to see if a loss of weight 

 accompanied pupal aging in them as well as in the silkworm 

 moth. The following table shows plainly the results of these ob- 

 servations : 



