102 BOARD OF AGRICULTURE. 
few days. The external skin, with the cilia, is then cast off, 
liberating a very different looking embryo or larva, which is 
provided with six boring hooks, similar to those of the em- 
bryos of ordinary tape-worms. Their subsequent history has 
not been ascertained, but it is probable that they enter some 
fish (most likely trout and salmon) and become encysted 
among the muscles, and that persons who eat imperfectly 
cooked or raw dried fish get the parasite in that way. 
It is remarkable that this species is not known to be indig- 
enous in any but European countries, and even in Europe it 
is peculiar to certain districts. It is particularly common in 
certain parts of Switzerland. In Geneva it is said that about 
one-fourth of all the inhabitants are afflicted with this worm. 
It occurs also in some parts of Russia, Poland, and Prussia. 
In America it has only been observed in-emigrants from 
Europe, and in persons who have traveled in the European 
countries where it naturally occurs. It causes similar symp- 
toms and is removed by the same remedies as the common 
tape-worms. 
TREMATODE WORMS. 
The Liver-fluke of Sheep and Cattle ( Fasciola hepatica Linn.). 
This common and notorious parasite has a very flat body, 
different on the two sides, and more or less oval in form, the 
anterior end suddenly narrowing to a sort of neck, which 
tapers off to the mouth end, where it is either rounded or 
pointed. The posterior end of the body is Figure 78. 
somewhat tapering, but blunt. Ordinary speci-’ Se 
mens are about three-quarters of an inch long 
and half an inch wide, but large ones become 
an inch and a quarter long and three-quarters || 
broad. While living they often curl up the ends 
of the body, toward the lower side. The color 
is pale brownish or greenish yellow, sometimes 
with a faint rosy tint. At the anterior end of 
the body there is a small, cup-shaped sucker, at 
the bottom of which the mouth is situated 
(Figure 78, a); near the origin of the neck- 
like portion, on the middledimeviobsdive lower side, there is 
“a 
