160 
Journal of Agricultural Research v 0 i. xxviii, No. 2 
much earlier than stated by Von Planta {85, 26). The young larvae receive a 
food rich in nitrogenous material and relatively low in sugar and in which pollen 
grains are absent during about the first two and a half days of larval life. A 
large part of this, which is several times in excess of the weight of the larva 
during the first 24 hours or more {35) (Table VIII), seems to be placed in the 
cell with the newly hatched larva at one time soon after hatching, which justifies 
the assumption of mass feeding. During this period, assimilation must be very 
rapid, because the greatest relative growth occurs during the first two to three 
days (Table VIII) and also because no unassimilated sugar can be demonstrated 
in the larva during t{iis period, even though the food contains about 5 per cent 
reducing sugar (Table V). The high nitrogenous content of the food apparently 
serves for rapid cell building, while the sugar is largely consumed in producing 
energy for this rapid growth; little storage of glycogen or fat occurs during this 
period. The nature and composition, as well as the biochemical reactions of 
this early food, as described by Koehler {25) , suggest that it is a glandular secre¬ 
tion rather than a regurgitation of predigested honey and pollen from the ven- 
triculus. The chances of larvae of this age during mass feeding receiving infective 
material are, therefore, slight. 
Table VIII. —Ratio of weight in milligrams of unconsumed food in cell to weight 
of larva at different approximate ages {from Sturtevant {85)) 
Approximate age (days) 
Number 
of ob¬ 
serva¬ 
tions 
Average 
weight 
of food 
per cell 
Average 
weight 
of larvae 
Average 
ratio, 
food to 
larva 
Egg.....-. 
Several. 
Milli¬ 
grams 
None. 
Milli¬ 
grams 
a 0.10 
0 
1.1.......... 
33 
3.96 
1.02 
3.88 
1.4......... 
131 
3.23 
1.36 
2.37 
2.1........... 
24 
9.10 
7.20 
1.26 
2.6............. 
35 
11.79 
17.48 
.67 
3.0....... 
25 
5.05 
25.22 
.20 
3.5 ..... 
65 
7. 75 
63.46 
. 12 
4.4..... 
17 
8.76 
115.15 
.08 
* From Nelson (So). 
Soon after the second day, a change in the composition of the food of the larva 
occurs, accompanied by a change in the method of feeding it by the nurse bees 
{26). The larva is now fed at approximately the rate at which the food is ingested 
by it, the demand for food rapidly increasing, accompanied by the great increase 
in actual body weight, until the time of sealing. The food now contains many 
entire pollen grains and has a much higher sugar content, nearly 14 per cent, 
and a relatively lower nitrogenous content (Table III). The principal ingredi¬ 
ents are now honey or nectar and pollen. It is well known that honey which is 
gathered while disease is present in the hive usually carries infection. There is, 
therefore, a much greater opportunity for infection to occur when the larvae are 
being given a food containing unmodified honey as one of its chief ingredients. 
Furthermore, the constant care of the larvae during the period of progressive 
feeding and the large number of nurse bees which visit the cell still further increase 
the chances of infection being introduced during the period of progressive feeding. 
It is the young bees in the colony which act as nurses, and these bees are also the 
ones which clean the hive, so that they are more apt to have infected material 
on their mouth parts and elsewhere than are old field workers. There can, 
therefore, be little doubt that it is almost exclusively during the period of pro¬ 
gressive feeding that infection normally occurs. Under normal feeding condi¬ 
tions the disease organisms can not develop in the larval intestine until after 
