267 
The experiments cited are too few to permit of formulating definite conclu- 
sions and it must not be forgotten that, purchased as they were — in open} 
market — their histories unknown, there may have occurred a considerable part 
of the bacteriological cycle before the specimens were investigated. The results 
given simply show what may happen to commercial ice cream if kept for from 
three to ten days. 
Two experiments have been made to test the action of freezing and thawing. 
For this work cream was obtained from a milk dealer, sweetened and flavored 
with vanilla in the laboratory, aud frozen in a small hand freezer, which had 
been cleansed simply with hot water. After freezing the product was packed 
down in an ice-salt mixture and allowed^ to stand until the cream had thor- 
oughly melted, though the temperature was still considerably below that of the 
surrounding atmosphere. It was then refrozen and again allowed to stand for 
some hours. At each step the bacterial count was made and recorded, as seen 
in Table II. Experiments of this character are of interest, not only for the trac- 
ing of decrease in numbers, but also as a possible source of information regard- 
ing the many cases of ice-cream poisoning blamed upon stale ice cream, and 
particularly that which had been melted and refrozen. 
Table I . — Growth of bacteria in ice cream at the temperature of ice and salt 
( —21° C. =—5.8°F.). 
SERIES I. 
Source of ice cream. 
Total number of organisms in — 
1 gram of 
fresh ice 
cream. 
1 gram after 
18 hours. 
1 gram after 
42 hours. 
1 gram after 
66 hours. 
No. 1— Manufacturer, sample sent directly 
from factory 
No. 2— Manufacturer, sample sent directly 
from factory 
No. 3— Manufacturer, sample sent directly 
from factory 
f a 811, 249 
( 52, 523, 886 
f a 4, 142,068 
i 59,521,995 
f a 3, 375, 527 
1 69,493,670 
al, 010, 509 
61,010,509 
a 2, 552, 676 
61,495,066 
a 4, 173, 622 
6936,065 
a 3, 349, 733 
6 628,074 
a 2, 603, 421 
6464,000 
a 1, 055, 966 
6422,386 
a 4, 405, 286 
61,664, 218 
a 4, 550, 050 
63,993,933 
a 4, 264, 870 
616, 835,016 
SERIES II. 
Total number of organisms in — 
Source of ice cream. 
1 gram of 
fresh ice 
cream. 
1 gram after 
24 hours. 
1 gram after 
48 hours. 
1 gram after 
96 hours. 
1 gram after 
192 hours. 
No. 4— Low-grade confectioner. 
No. 5 — Wholesale milk com- 
pany and dairy lunch 
f a 564, 381 
1 61,097,408 
f al, 006, 904 
{ 65,418,105 
a 164, 000 
6201, 786 
al, 489, 361 
6 2, 765, 957 
a 140, 814 
61, 804, 180 
a 1,171, 613 
62,454,809 
a 149, 812 
62,536,115 
a 816, 405 
6 3,936, 242 
a61,312 
61,021,867 
a236,709 
SERIES III. 
Total number of organisms in — 
Source of ice cream. 
1 gram of 
fresh ice 
cream. 
1 gram after 
24 hours. 
1 gram after 
48 hours. . 
1 gram after 
72 hours. 
lgram after 
120 hours. 
lgram after 
216 hours. 
No. 6 — Cheap restaurant 
| a 2,668,777 
a 298, 804 
a 709, 442 
a 690, 00U 
a 292, 839 
a 153, 351 
which buys from manu- 
facturer of sample No. 1. 
I 5 6,219,608 
51,090, 637 
5 855, 503 
51,189,296 
5 2, 352, 163 
5 946,611 
No. 7 — Small bakery, prem- 
fa 12,460,196 
a 3, 231, 017 
a 4, 019, 523 
a 12, 735, 849 
a 8, 052, 455 
a 644, 329 
ises clean 
No. 8 — Market-house lunch 
{ 5 29, 558, 355 
5 2, 670, 974 
5 8, 010, 335 
5 2, 452, 830 
5 2,300,701 
5 5, 257, 731 
counter, ice cream made 
1 a 510, 673 
a 1, 256, 645 t 
a 1,424, 936 
a 776, 196 
a 476, 338 
a 219, 499 
by proprietor 
[ 5 714,942 
5 2,319,961 , 
51,323,155 
5 217, 335 
51,449,725 
5 1, 005, 615 
a 37° C. b 18° to 20° C. 
