II20 PROTEIN METABOLISM [pt. m 



Farkas, although mainly concerned with the respiration and 

 the calorific value of the silkworm egg at different stages, also 

 estimated the total nitrogen in the eggs. In his first experiment a batch 

 of 33*0 gm. of eggs (about 280 individuals) contained 1-27 gm. of total 

 nitrogen before development, and 1-26 gm. at hatching — a constancy 

 probably within the limits of error. His second experiment gave a 

 different result, however, the total nitrogen falling from 1-84 gm. 

 to I '54 gm. for a batch of 45-87 gm. of eggs. Farkas' explanation 

 for this was that during the last few days of development the larvae 

 were hatching irregularly, and some were dying, so that a mass of 

 excreta, egg-shells, and dead larvae, all saturated with condensation 

 water, remained on the floor of the incubation chamber. In this 

 mass, micro-organisms were doubtless decomposing the uric acid. 

 This explanation might go some way towards explaining Russo's 

 decline in total nitrogen. Furthermore, it was shown by Peligot for 

 the silkworm and by Henneberg for the bee that no ammonia was 

 given off by the eggs as they develop. Farkas consequently affirmed 

 that there was no nitrogen loss from the eggs, and that the missing 

 0-27 gm. of nitrogen in his second experiment was all uric acid. 

 Further and more accurate observations would be very desirable in 

 this confused subject. Farkas calculated from his calorimetric 

 measurements that 63-4 per cent, of the total material catabolised 

 in the silkworm egg was fat, and 36-6 per cent, not fat; and for this 

 latter fraction he calculated a specific energy of 7-31 Cals. On this 

 basis alone (the specific energy of protein being 7-9 Cals.) he con- 

 cluded that most of the 36-6 per cent, was protein. It is not sufficient 

 evidence. 



Table 155. Russo's figures for the silkworm. 



More reliance, perhaps, can be placed upon Russo's figures for the 

 distribution of nitrogen. These are interesting, for they show prac- 

 tically no change till the end of the diapause (as might be expected, 

 the morphological work done till the end of that period being so 



