SEVENTH ANNUAL REPORT. 141 
Thorough cooking kills the cysticercus, rendering it harmless. 
It has been demonstrated by several experimenters that a tem- 
perature of from 55°—65° C.(131° Fr.—149° Fr.) is sufficient to 
kill the parasite. In some of the German abattoirs, where the 
carcasses of animals affected with cysticerci are considered fit for 
food, the meat is cut into suitable pieces and thoroughly sterilized 
(in large ovens built for this purpose) before being exposed 
for sale. 
In this country, where the custom is to cook the meat more 
or less thoroughly before eating it, the chances of an individual 
becoming infected with taenia are not so great. With the ex- 
ception of the heart, Cysticercus cellulosa are seldom found in in- 
ternal organs, while fat tissue is nearly always free from them. 
CYSTICERCUS TENNICOLLIS. 
This hydatid is found in all domestic and wild ruminants, but 
is probably most commonly met with in sheep and deer. The 
progenitor of this hydatid, Taenia marginata, inhabits the intes- 
tines of the dog, fox, and wolf. 
This hydatid is sometimes confounded with the Cysticercus cel- 
lulosa, but it has a number of characteristic features which differ 
very materially from those of the latter, for which it should not 
be mistaken. 
The size of the cyst depends upon its age and situation. If 
situated upon serous membranes (which is usually the position 
of this hydatid), lining closed cavities where little or no pressure 
is exerted upon them, they may reach the size of a hen’s egg, or 
even larger. 
In the case of the mule deer, the cysts of which show so well in 
the photograph, the largest cyst was about the size of a bantam’s 
egg. In this case the cysts were contained in a sac, apparently 
formed from the peritoneal tissue, and having the appearance of 
small water bladders, and at the point of attachment there was 
a constricted portion produced by the weight of the fluid con- 
tained in the cyst. The outline of the scolex could be distin- 
guished through the walls of the cyst, but not as plainly as through 
a cyst containing Cysticercus cellulosa. 
In a series of experiments carried out by Leuchart, he found 
that cysts attained the length of .6 to 3.5 m.m. in ten days 
