844 
Journal of Agricultural Research 
Vol. V, No. 18 
gonad were rounded instead of being closely pressed together as in the 
normal trichina. Two out of five test rats were negative, the three others 
contained 4,7, and 20 trichinae, respectively, in the diaphragm. 
In experiment 94, in which the meat had been exposed to a tempera¬ 
ture of 5 0 to 6.5° F., 204 trichinae were examined, 199 of which were 
inactive, and only 5 of which showed any activity when warmed, this 
consisting of a very slight movement on stimulation with a needle point. 
The coils were expanded in the form of a figure 6, or in some instances 
formed a very loose spiral. The esophageal cellular body was very pale 
in color, granulation of the protoplasm very abnormal, nuclei solidified, 
quite different in appearance from the normal vesicular nucleus. The 
cells of the gonad were rounded and more or less dissociated. Five test 
rats fed in this experiment all failed to become infested. 
The abnormal granulation of the cellular body referred to is difficult to 
describe, but it gives the protoplasm a distinctly different appearance 
from that of the cellular body of an unfrozen trichina, dull and dead¬ 
looking as compared with the bright appearance of the latter, the visible 
particles being much more numerous and smaller. 
Comparison of the results of these three experiments and similar 
experiments shows not only that microscopically visible changes occur 
in the minute structure of trichinae subjected to temperatures of 15 0 F. 
and lower, but that these changes are more pronounced in trichinae sub¬ 
jected to about io° than in those subjected to about 15 0 , and still more 
pronounced in trichinae subjected to about 5 0 . These changes are evi¬ 
dently brought about by the low temperature, but in what way is not 
apparent. This problem probably belongs in the field of colloid chem¬ 
istry. Thereoccurs perhaps a precipitation of the colloids in the tissues 
of the trichina or some change in their nature which is more or less irre¬ 
versible, according as the temperature is lower or higher and the period 
of exposure longer or shorter. In those cases in which the trichinae were 
examined very soon after thawing of the meat (experiments 1 and 3, 
for example) it was quite evident from the shriveled appearance of the 
parasites that fluid had been extracted from them during their exposure 
to cold. Trichinae thus shriveled absorb moisture after thawing and 
soon lose their shriveled appearance, again becoming active unless the 
temperature was too low and the period of exposure to cold too long 
continued. In some respects trichinae which have been frozen at a low 
temperature (5 0 F.) resemble those which have been dried and then 
moistened again. Ordinary drying, however, destroys the vitality of 
trichinae immediately, and the changes produced are much more marked 
than those produced by freezing. It is possible that the latter might 
be more closely simulated if the trichinae were very gradually dried and 
the drying process stopped at the proper point. As yet, however, careful 
experiments along this line have not been carried out. 
