Jan. 31,1916 
Effects of Refrigeration on Trichinella spiralis 
847 
because of the longer periods elapsing since the removal of the meat 
from the freezer, inasmuch as in other experiments in which the period 
of exposure in the freezer had been about the same but in which the 
meat was fed more promptly positive results were obtained in the feeding 
tests—i. e., in experiments 31, 122, 123, and 121, the periods elapsing 
between removal from the freezer and the first feeding of test animals 
being 2, 2, 2, and 3 days, respectively. This comparison, however, is 
not of great value, since in experiments 15, 28, 27 (meat in freezer at 
about 15 0 F. for 12 to 13 days), and 125 (meat in freezer at about 15 0 
for 22 days) in which the meat was fed 2,5,5, an d 4 days, respectively, 
after removal from the freezer, the results of the feeding tests were 
negative. 
Further investigation is required to determine the changes which occur 
in the vitality of trichinae when frozen meat is kept for varying periods 
of time after thawing. From the data at present available, however, it 
is quite certain that if any considerable changes occur, they are in the 
direction of a lowering of vitality and not in the reverse direction. 
In this connection it is of interest to note that in unfrozen meat kept 
over three months after slaughter the trichinae had suffered no evident 
loss in vitality, and small quantities of the meat were sufficient to produce 
heavy infestations in rats (controls, experiments 91 to 126). On the 
other hand, in meat kept nearly eight months after slaughter the trichinae 
had lost their vitality, and test rats failed to become infested (controls, 
experiments 72 to 76). 
EFFECTS OF ARTIFICIAL, DIGESTION UPON TRICHINAE 
As evident from the tabular statement of the experiments (control 
examinations), artificial digestion for 24 hours or less had no appreciably 
injurious effect upon the vitality of trichinae. When digested for two 
days, however, a considerable proportion of the trichinae are liable to be 
killed (experiment 32). On the other hand, if 5 or 6 gm. of salt are added 
to each liter of digestive fluid the vitality of the trichinae is not so seriously 
affected. The trichinae from unfrozen meat digested for two days in 
experiment 96 seemed as lively as usual. Trichinae, however, from meat 
frozen for 16 days at about 15 0 F. in experiment 120 evidently suffered 
considerably from digestion for two days, inasmuch as a smallef propor¬ 
tion were active and these were less lively than trichinae examined in 
experiments 121, 122, 123, from meat frozen 17, 18, and 20 days, respec¬ 
tively, at about 15 0 F. and digested less than 24 hours. Furthermore, the 
fact that prolonged digestion in a digestive fluid containing 0.5 per cent 
of sodium chlorid is injurious to trichinae from unfrozen meat was shown 
by an experiment in which digestion was continued for four days. In 
this instance all of the trichinae were killed. 
Though it is possible that the methods of artificial digestion employed 
in the experiments to free trichinae from meat for examination reduced 
