Journal of Agricultural Research 
Vol. XXVII, No. 3 
168 
For io days: 
Above zero (27.5 0 to 32 0 F.). culture 6. 
Below zero (o° to —16 0 F.).culture 7. 
For 20 days below zero (—14 0 to +5° F.) 4 .culture 8. 
For 30 days below zero (—14 0 to -j-5 0 F.) 4 .culture 9. 
For 40 days: 
Above zero (io° to 18 0 F.).culture 10. 
Below zero (—2 0 to —16 0 F.).culture 11. 
After being thus exposed to freezing temperatures, the cultures were 
thawed, covered with potassium bichromate (10 per cent), and kept in an 
incubator at 24 0 C. In every case the eggs developed into active em¬ 
bryos, and neither the length of exposure to the cold nor the degree of 
cold itself seemed to affect the rate of development when the eggs were 
restored to 24 0 C. Cleavage appeared in 3 to 5 days, reached the many- 
celled stage in 6 to 8 days, and the motile embryos developed in 13 to 
15 days. Although the low temperature in some cases seemed to break 
up the protoplasm of the egg so that it lost its normal appearance, this 
evidently did not interfere with the development, as cells with this 
appearance decreased in number or disappeared altogether during the 
incubation. 
Although active embryos developed in all the tests, in the last, those 
for 40 days above and below zero F., the embryos seemed to be short¬ 
lived; on the sixth day after motion was first observed only a very few 
of the many embryos showed any activity. Apparently this prolonged 
exposure impaired the vitality of the worms, and it seems probable that 
the infectivity of such worms would be lessened. 
TESTS TO DETERMINE THE RESISTANCE TO VARYING FREEZING TEM¬ 
PERATURES OF PARTIALLY INCUBATED ASCARIS LUMBRICOIDES EGGS— 
THE EGGS SHOWING VARIOUS STAGES OF CELL DIVISION 
A scar is lumbricoides eggs, developed at 24 0 C. to various stages of 
cleavage, were held at freezing temperatures as follows: 
For 7 days: 
Above zero (8° to 12 0 F.).culture A 
Below zero (—2° to —16 0 F.).culture A / 
For 20 days: 
Above zero (io° to 16 0 F.).culture B 
Below zero (—2 0 to —16 0 F.).culture B 7 
After being kept at these freezing temperatures for the periods of time 
stated, the cultures. were covered with a 2 per cent formalin solution 
and kept in the incubator (24 0 C.). All four cultures developed active 
embryos, and apparently all the eggs, at whatever stage of cleavage when 
put in the freezer, resumed their development when again incubated at 
24 0 C. That the freezing shortened the life of these embryos was indi¬ 
cated, however, in the second set of tests, those for 20 days above and 
below zero F. The activity of the developed embryos was quite limited; 
24 days after motion was first observed very few embryos could be 
found which showed any activity. 
However, the viability of such embryos, developed from eggs which 
had been below zero F. for 20 days while in various stages of segmenta¬ 
tion, was demonstrated in the following series (C) of tests—in culture 
F'; the embryonated eggs were fed to a guinea pig and an infection 
produced in the lungs. 
4 The temperature rose above zero for a brief period in the afternoon on three days. 
