260 BEVERLY WAUGH KUNKEL 



flesh flies, although the acceleration is not great. In one excep- 

 tional case, that of egg mass No. 28 of L. caesar there was a slight 

 retardation in pupating effected by thyroid feeding. My record 

 in this experiment shows that on the sixth day after deposition of 

 eggs, the muscle larvae were all buried while the thyroid larvae 

 were in process of burial. The following day 8 per cent of the 

 thyroid larvae had pupated and 16 per cent of the muscle larvae. 

 On the other hand, eighteen days after the deposition of the eggs, 

 the thjToid-fed had outstripped the muscle-fed, for 57 per cent 

 of the former had emerged and only 18 per cent of the latter. 



Egg mass No. 16 of L. caesar, in which the thyroid-fed larvae 

 were markedly smaller than the muscle-fed affords evidence that 

 thyroid feeding accelerates development. Ten days after depo- 

 sition of eggs, the thyroid culture contained 94 pupae and 1 

 larva, while the muscle culture contained only 43 pupae and 11 

 larvae. That is, 99 per cent of the larvae had pupated in the 

 thyroid and only 80 per cent in the muscle culture. 



Egg mass No. 9 also indicates that the pupal period may be 

 shortened slightly by thyroid feeding. In both experimental 

 and control cultures pupation was first noted on the tenth day 

 following the deposition of the eggs. On the fourteenth day, 

 five out of fourteen pupae had opened while none of the muscle 

 pupae had matured. Within eighteen days after the deposition 

 of the eggs all ten flies from the muscle-fee larvae had emerged, 

 but the rest of the thyroid-fed were dead. 



Egg mass No. 16 also affords some evidence that the pupation 

 period may be slightly shortened by thyroid feeding. Fourteen 

 days after deposition of eggs, 43 out of 94, 46 per cent, of the 

 thyroid pupae had emerged while in the same time only 2 out of 

 50, 4 per cent, of the muscle pupae had emerged. Two days 

 later there were 36 muscle flies emerged and 88 thyroid flies, or 

 72 per cent of the muscle-fed flies had emerged in the same time 

 that 93 per cent of the th>Toid-fed had. 



Egg mass No. 22 of L. sericata also shows that there is a slight 

 hastening of pupation effected by thyroid feeding. Six days 

 after egg deposition there were found in the muscle culture 

 5 pupae and 57 larvae which had buried themselves, while in the 



