14 
AN INTERESTING CASE OF CYSTICERCUS FARC 10- 
LARIS INFESTING THE BROWN RAT. 
By A. T. HOPWOOD, 
Assistant in Zoology , West Virginia University , Morgantown , W. Va. 
(With Plate I.) 
Cystic erous fasciolar is, the larval stage of the common tapeworm Taenia 
taeniaeformis (T . crassicolis), was recently found in great numbers in the liver 
of a brown rat. The rat measured 18 cm. in length and weighed about 275 g.; 
it was vigorous and apparently healthy when caught, but when killed and 
examined, its liver was found to be heavily infested with the cysticerci. 
This cestode in itself is common enough, but the great number of cysticerci 
attracted attention. On the ventral surfaces of the ventral lobes of the liver 
which are shown in the photograph (PL I), 108 of the cysts were visible and 
this region was the least infested. The dorsal surfaces of these lobes as well 
as the entire surfaces of the others harboured cysts almost to their full capacity. 
It is difficult to conceive how many more of the larvae could possibly have 
found room to encyst themselves. There was visible a total of 256 larvae, about 
50 of which were visible from both surfaces. Many more may have been 
embedded in the tissue and invisible from either surface. 
Possibly not more than nine-tenths of the liver was incapacitated and the 
bile ducts were not greatly obstructed, which probably explains why the 
animal was still apparently healthy. The cysticerci were identified in the 
laboratory and their determination was confirmed by reference to the Zoo¬ 
logical Division of the Bureau of Animal Industry of the U. S. Department of 
Agriculture. 
