268 
Table II . — Bacterial growth in ice cream thawed and refrozen. 
Source of ice cream. 
Total nvunber of organisms in — 
1 gram of 
cream. 
1 gram of ice 
cream. 
1 gram of i 
melted ice 
cream 14 
hours after 
freezing. 
1 gram of re- 
frozen cream. 
1 gram of ice 
cream 7 
hours after 
refreezing. 
Experiment!— Home-made, va- 
nilla 
j al, 142, 640 
1 61,158,886 
a 274, 254 
6351,219 
a 57, 090 
6331, 125 
a 32, 829 
6 306,412 
« 28, 774 
632, 696 
Source of ice cream. 
Total number of organisms in — 
1 gram of 
cream. 
1 gram of ice 
cream. 
1 gram of 
melted ice 
cream 23 
hours after 
freezing. 
1 gram of re- 
frozen cream. 
1 gram of ice 
cream 5 
hours after 
refreezing. 
Experiment 2— Home-made, va- 
nilla 
J a 2, 926, 421 
1 67,525,125 
al,144, 016 
63,874, 896 
a 897, 867 
62,244, 668 
0 614,463 
6732,629 
01,541,501 
a37°C. fcl8°to20oC. 
All of the samples which have been studied for cold storage his- 
tory were examined also for the presence of streptococci. The re- 
sults are indicated in the following list : 
Num- 
ber. 
Streptococci. 
Num- 
ber. 
streptococci. 
1 
Not found. 
5 
Present — short chains — few. 
2 
Present— short chains— numerous. 
6 
Present — long chains — numerous. 
3 
Present — long chains — very numerous. 
7 
Not found. 
4 
Present — short chains — few. 
8 
; Not found. 
1 
Eighty-two and five-tenths per cent showed the presence of the 
organism. 
The method for the detection of streptococci in ice cream was as 
follows: The melted sample was centrifuged for half an hour in a 
Stewart lactocrite driven by a small motor of such power that the 
speed was approximately 3,000 revolutions per minute. This appa- 
ratus, which consists of a flat aluminum pan holding 20 tubes of 1 
cubic centimeter capacit}^ and stoppered at the outer end Avith a spe- 
cially constructed rubber plug, causes the sediment not only to be 
throAvn to the end of the tube but drives it against the rubber plug 
with such force it is almost quantitatively adherent to the plug. 
Accordingly, if one carefully remoA^es the rubber stopper and by rub- 
bing on a glass slide and OA^er an area of known surface attaches the 
sediment, one can obtain, on staining and examining the film micro- 
scopically, an approximation of the number of organisms and leu- 
cocytes in 1 cubic centimeter of the liquid. 
