Jan. 19,1924 
Influence of Low Temperatures on Ascaris Eggs 169 
TESTS To DETERMINE THE RESISTANCE TO VARYING FREEZING TEM¬ 
PERATURES OF ASCARIS EUMBRICOIDES EGGS CONTAINING ACTIVE 
EMBRYOS 
Two sets of cultures were kept in freezers, one above zero and one 
below zero, for the following lengths of time: 
For 1 day: 
30° to 32 0 F. 
—13 0 to —17 0 F 
For s days: 
30° to 36° F. 
—8° to —17 0 F. 
For 10 days: 
8° to 16 0 F. 
—2 0 to —16 0 F. 
For 20 days: 
7 0 to 16 0 F. 
—6° to —1 7 ° F. 
For 30 days: 
12 0 to 18 0 F. 
—4 0 to —14 0 F. 
culture C. 
.culture O'. 
culture D. 
.culture D'. 
.culture E. 
culture E / . 
culture F. 
culture F / . 
culture G. 
culture G / . 
Table I .—Detailed tabulation of tests 
State of egg before 
freezing. 
Culture 
number. 
Temperature to which 
exposed. 
Period of 
time (days). 
Result after restored to 
a 4 ° C. 
Fresh. 
I 
— 7 0 to —il° F. 
I 
Developed into ac¬ 
tive embryos. 
Do. 
2 
-2° to +2° F. 
2 
Do. 
Do. 
2 
27 0 to 28° F. 
cr 
Do. 
Do. 
O 
4 
8° to ii° F. 
0 
Do. 
Do. 
■ 
5 
—0.5 0 to —ii° F_ 
5 
Do. 
Do. 
6 
27. S° tO 22° F. 
10 
Do. 
Do. 
7 
o° to —16 0 F. 
10 
Do. 
Do. 
8 
-i 4 °to -H°F. 
20 
Do. 
Do. 
0 
*T i 3 * * • 
-14° to -H° F. 
20 
Do. 
Do. 
IO 
io° to 18 0 F. 
40 
Do. 
Do. 
11 
-2° to —16 0 F. 
nr' 
40 
Do. 
Partially incubated... 
A 
8° to 12° F . 
7 
Do. 
Do . 
A / 
— 2 0 to —16 0 F . 
7 
Do. 
Do .. 
B 
io° to 16 0 F . 
20 
Do. 
Do . 
B' 
—2 0 to —16 0 F . 
20 
Do. 
Containing active 
C 
30° to 32 0 F . 
1 
Activity. 
embryos. 
Do . 
C' 
—13 0 to —17 0 F _ 
1 
Do. 
Do . 
D 
20 0 to 26° F . 
c 
Do. 
Do . 
D / 
—8° to —17 0 F . 
0 
c 
Do. 
Do . 
E 
8° to 16 0 F . 
0 
XO 
Do. 
Do . 
W 
— 2 0 to —16 0 F . 
IO 
Do. 
Do . 
p 
7 0 to 16 0 F . 
20 
Do. 
Do . 
F / 
-6° to -17 0 F . 
20 
Inactive. 
Do. 
G 
12 0 to 18 0 F. 
20 
Active. 
Do. 
G / 
— 4° to —14 0 F. 
O 
30 
Inactive. 
All five cultures kept above zero F. for the stated periods showed 
active embryos after thawing. Of those kept below zero F. the first 
three (those of the i-day, the 5-day, and the 10-day periods) showed 
active embryos. However, that the infectivity of these embryos was 
diminished was indicated by the fact that neither the culture kept below 
