822 
Journal of Agricultural Research 
Vol, V, No. 18 
EXPERIMENTAL WORK 
DESCRIPTION OP EXPERIMENTS 
The first experiment was carried out in Chicago in September, 1913. 
The carcass of a naturally infested trichinous rat killed on September 11 
was inclosed in a tin can and kept in a refrigerator until September 16, 
when it was placed in a refrigerated compartment known as a “freezer” 
in one of the meat-packing establishments, where it remained for nearly 
6 days—i. e., 5 days, 22 hours. During this time the temperature (as 
recorded by a thermometer not compared with a standardized thermome¬ 
ter), read once daily; varied from — 3 0 to — io° F. 1 When removed, the 
rat carcass was allowed to thaw by exposure to ordinary room tempera¬ 
ture, after which eight trichinae were isolated by dissection. Examined 
in water on a warm stage, they were found to be shrunken and motionless. 
They were left in a moist chamber and again examined the following day, 
when they were found to be no longer shrunken, but exhibited no move¬ 
ment. Two more trichinae, isolated from the meat the day after removal 
from the freezer, were also found to be inactive. A guinea pig was fed 
some of the meat from the rat carcass on September 25 and was found to 
be free from trichinae when examined on October 25. 
The failure to discover any evidence of life among the trichinae isolated 
from the frozen rat carcass led to further experiments. 
In experiment 2, a small piece of the diaphragm of another trichinous 
rat, after the carcass had been kept in an ice box for 11 days, was sealed 
in a vial and kept in a freezing mixture at a temperature of 4 0 to io° F. 
for 30 minutes. No active trichinae were found on examination after 
thawing. The rest of the carcass of the same rat was then inclosed in a 
tin can and placed in a freezer maintained at a temperature of 13 0 to 15 0 F . t 
recorded by means of a thermometer (six readings daily), afterwards 
compared with a standardized thermometer (experiment 3). After 
nearly 2 days (45^ hours) the can was removed from the freezer. 
Trichinae isolated by dissection soon after the meat had thawed and ex¬ 
amined in water on a warm stage were found to be shrunken and motion¬ 
less, but resumed their normal appearance and became active in 10 to 30 
minutes. 
In experiments 4, 5, and 6, pieces of diaphragm of an artifically infested 
rabbit were sealed in small vials and exposed to a temperature of — 6° F. 
for 10, 20, and 30 minutes, respectively; none of the trichinae isolated by 
dissection from the meat after thawing showed any activity, and guinea 
pigs fed with the meat failed to become infested. 
In experiment 7 the carcass of a naturally infested rat was kept in a 
tin can in a freezer at 13 0 to 15 0 F. (six readings daily; thermometer 
1 Because of the practical bearing of the experiments upon the meat-packing industry, refrigeration 
temperatures are given according to the Fahrenheit scale, which is the only temperature scale in common 
use in the United States. 
