Apr. 12,1924 
Devebpment of American Foulbrood 
161 
feeding has ceased and the sugar-containing food has largely been assimilated, 
because, with the rate at which the larva is given food containing about 14 per 
cent sugar, the sugar concentration in the intestine must rapidly increase beyond 
the 3 to 4 per cent concentration which inhibits growth, so as to prevent the 
development of the disease in the larva. From Tables IX and X it may be seen 
that from the second day on, increasing numbers of visits are made to the larva 
with an increasing amount of time spent in nursing (Table X), so that on the 
last day of feeding a nursing visit, averaging six seconds in duration, is made 
approximately every 30 seconds, or an average total during the last 24 hours of 
2,855 visits, or 36 per cent of the average 7,858 visits made during the entire 
feeding period (Table IX). The rapid consumption of this great amount of 
food, which is supplied in almost a steady stream, is indicated by the fact that 
the amount of food in the cell with the larva decreases to less than 10 per cent 
of the weight of the larva just prior to sealing. Even though the exact amount of 
food consumed may not be known, the actual concentration of sugar in the 
intestine during this period must rapidly rise, because of the high concen¬ 
tration of sugar in the food and the volume at which it apparently is fed to the 
larva, to several times the concentration necessary to inhibit the growth of 
Bacillus larvae. There is, as mentioned above, a diluting factor due to the 
accumulation of undigestible material until the connection is made with the 
end intestine, but, as shown by the microscopical examination of the intestinal 
contents, this, because it is largely insoluble, is probably of relatively slight 
importance in its effect upon the actual sugar concentration in the intestine 
during the period when inhibition occurs. 
Table IX.— Relation of nursing to increase in weight of larva a 
Average 
daily 
ratio of 
increase 
to pre¬ 
ceding 
weight 
During active feeding 
period 
Age (days) 
Average 
weight 
of larvae 
Average 
daily 
increase 
Number 
of visits 
in 24 
hours 
Average 
increase 
in weight 
per visit 
per 24 
hours 
Egg....... 
Gram 
0.000100 
Gram 
Gram 
1.... 
.000650 
0.000550 
5.5 
921.6 
0.000000597 
2..... 
.004745 
.004095 
6.3 
833.8 
.00000492 
3...... 
. 024626 
. 019881 
4.19 
1163.5 
.00001709 
4...... 
.093990 
.069364 
2.82 
2083.7 
.00003329 
5.. 
. 146748 
.052758 
.56 
2855.5 
.00001848 
6.... 
. 155005 
.008257 
.06 
a From Sturtevant ( 85) and Lineburg {26). 
Table X.— Time spent in feeding a 
Age (days) 
Average 
time 
spent in 
nursing 
per visit 
per 10 
minute 
period 
Average 
number 
of visits 
per 10 
minute 
period 
Average 
number 
of seconds 
per visit 
Average 
frequency 
of visits 
Average 
number 
of seconds 
between 
visits 
Seconds 
Seconds 
Seconds 
Seconds 
1.... 
20.73 
6.40 
3.2 
93.7 
90.5 
2_______ 
5.93 
5.79 
1.0 
103.6 
102.6 
3_:___ 
11. 42 
8.08 
1.4 
74.3 
72.9 
4.... 
41.00 
14. 47 
2.8 
41.5 
38.7 
5....... 
118.08 
19.83 
5.9 
30.3 
24.4 
o Calculated from Lineburg ( 26 ). 
