Apr. 12,1924 
Development of American Foulbrood 
145 
Table IV .—Average chemical composition of worker larvce at different ages , compiled 
from Straus (48 ) 
Age 
Weight 
of larva 
Glycogen 
Fat 
Nitrogen 
Reducing 
sugar 
Grams 
per larva 
Per cent 
of fresh 
substance 
Grams 
per larva 
Per cent 
of fresh 
substance 
Grams 
per larva 
Per cent 
of fresh 
substance 
Day8 
1. 
Grams 
0.00030 
.00340 
.03000 
.10010 
. 12775 
.14290 
. 16140 
.14300 
.14200 
.14500 
.13000 
2. 
0.00008 
.0012 
.0055 
.0072 
.0088 
.0092 
.0089 
.0075 
.0075 
.0056 
2.50 
2.75 
5.58 
5.57 
6.95 
6.43 
6.35 
5.21 
5.24 
4.21 
0.00004 
.00005 
.0031 
.0047 
°.0057 - 
.0060 
.0051 
.0052 
.0049 
.0047 
i. 53 
1.64 
3.60 
3.64 
0 3.98 
3.71 
3.53 
3.66 
3.60 
3.26 
0.00009 
.0005 
.0016 
.0016 
.0019 
.0018 
.0027 
.0022 
.0022 
.0023 
2.86 
2.04 
1.44 
1.47 
1.45 
1.22 
1.51 
1.60 
1.58 
1.68 
3. 
4. 
5. 
0 
6. 
7. 
Trace. 
Trace. 
8. 
9. 
10. 
0.0002 
11. 
° Calculated by interpolation and averaging. 
CHOICE OF REAGENT 
It was necessary to devise a special technic for the determination of the unassimi¬ 
lated reducing sugar in the larva by the application of procedures used in other 
analyses where small amounts of reducing sugars must be determined, such as in 
urine analysis. After studying the various methods of sugar analysis, a volumetric 
titration method seemed the most promising. 
For the purpose of determining quantitatively the unassimilated sugar in the 
bee larva at different ages, the modified copper sulphate solution of Benedict (5) 
was chosen, mainly because, as in urine analysis, it has proved more satisfactory 
than any other titration method for determining small amounts of reducing 
sugars quantitatively, and because this solution keeps indefinitely without 
deteriorating. The potassium sulphocyanate in the solution produces, upon 
reduction of the sugar, a white precipitate of cuprous sulphocyanate, which per¬ 
mits the end point of the reaction to be more accurately determined than with 
Fehling’s solution. A trace of ferrocyanid is added to prevent precipitation of red 
cuprous oxid which may be caused by certain impurities, which would interfere 
with the determination of the end point. The test solution is standardized to a 
known solution of dextrose so that 5 cc. equals 0.0102 grams of dextrose. 
CHOICE OF LARVAE 
Since there is little likelihood of there being any appreciable amount of sugar 
elsewhere than in the intestine, analyses were made of entire larvae, because of 
the great difficulty attending the dissection of the intestines. Larvae for analysis 
were chosen from combs having large areas of brood of uniform size and age. In 
most cases 25 larvae as nearly of the same size as possible were carefully removed 
from the cells by means of a pair of fine forceps, care being taken to remove as little 
uningested food as possible. Any visible amount of adhering food was removed 
with filter paper and the 25 larvae were weighed. Several series were weighed for 
each age above the two-day age period through to about the fourth day after 
capping. 
DETERMINATION OF AGE OF LARVAE 
When choosing larvae for the analysis, the approximate age was determined by 
comparison with drawings to scale by Nelson and Sturtevant (35) of larvae of 
known age at various age periods, 24 hours apart. Nelson and Sturtevant, as 
