148 



Journal' of Agricultural Research voi. xxviii. No. 2 



Table V. — Unassimilated sugar in intestinal content of larvx at different ages — 



Continued 



<: Total extract, 100 cc. 



« All sealed, coiled or with backs out. Feeding ended and spinning of cocoons started. 



* Cocoon partially spun, still some color in the intestine. 



i Cocoon not quite finished, still moving somewhat, no color in intestine. 

 i Quiescent prepupae, intestines colorless, empty, histolysis started. • 



* First indication of change in external form. 



OBSERVATIONS 



Over 60 samples of 25 larvae each of various ages, containing over 1,600 indi- 

 vidual larvae, were analyzed for the presence of reducing sugars. The largest 

 number of analyses were made on larvae from 3i to 6J days of age during the 

 active honey and poUen feeding period. At least five analyses were made of 

 each of the other age periods which might show the presence of sugar. To obtain 

 averages with a small probable error, the analyses are grouped by age periods of 

 24 hours each, as described earlier (Table V, fig. 13). All larva in the two- 

 day group, as well as one sample of larvae nearly as heavy as the three-day aver- 

 age larva, showed no reducing sugar. Larvae in the three-day group, averaging 

 0.043222 gm. in weight, gave 0.000475 gm. of reducing sugar per larva, or 

 0.98 per cent concentration. Larvae in the four-day group, averaging 0.10314 

 gm. in weight, gave 0.00299 gm. of reducing sugar per larva, or 2.82 per cent 

 concentration. Larva; in the five-day group, comprising those just prior to 

 seahng, with a few just sealed, averaging 0.13591 gm. in weight, gave 0.00428 

 gm. of reducing sugar per larva, or 3.14 per cent concentration. In the five-day 

 group there were two samples which gave a concentration of over 4 per cent, the 

 maximum being 4.41 per cent. The six-day group, comprised entirely of larva 

 that had been sealed, had finished feeding and had started spinning, averaging 

 0.15581 gm. in weight, gave 0.00372 gm. of reducing sugar per larva, or 2.39 per 

 cent concentration. This group contains larvae of maximum size (fig. 14). From 



