20 Farmers’ Bulletin 1150. 
TAPEWORMS. 
Adult tapeworms are usually composed of a head, armed with 
hooks and suckers as a rule (though those in the sheep’s intestines 
xnave no hooks), and a body consisting of a number of flat segments 
arranged in a chain. Adult tapeworms are usually found in the 
small intestines, but in some cases they may occur in the stomach, 
large intestines, or the ducts of the liver and pancreas. Tapeworms 
produce eggs of microscopic size which pass out in the feces and 
which on being swallowed by a suitable host, usually of a sort dif- 
ferent from the host of the adult tapeworm, give rise to an inter- 
mediate stage, or larva, which is usually more or less spherical or 
elliptical and composed of a tapeworm head and neck attached to a 
membrane, the membrane usually inclosing a clear fluid. In the case 
of many of the common tapeworms this form is called a bladder- 
worm. It usually occurs in the body tissues, and when these are 
eaten by the host of the adult tapeworm the head of the tapeworm 
passes to the intestine and forms the adult worm by the addition of 
segments back of the head. This tapeworm in turn produces eggs 
and the cycle is repeated. Thus, certain tapeworms in the dog give 
rise to certain bladderworms in asd the tapeworm eggs in thes feces 
of the dog being deposited on the pasture and picked up by sheep 
with the herbage that they eat. The dog in turn becomes infested 
with tapeworms when it eats the bladderworms in the meat, brain, 
liver, entrails, or other parts of the sheep. 
Sheep may harbor adult tapeworms in the intestine aad bladder- 
worms in the body tissues. 
THE MONIEZIAS.® 
Location.—These tapeworms are found in the small intestines. 
Appearance.—They are whitish to yellowish in color and may 
attain a length, in some specimens, of several yards (see fig. 13). 
The individual segments of a worm are broader than long, and 
each segment contains at some period of 1ts development a complete 
set of reproductive organs. The end segments are full of eggs, and 
these segments break off from the rest of the worm and pass out in 
the manure, where they are often found by the farmer and regarded 
as complete worms. The presence of these segments in the feces 
serves to diagnose cases of infestation with the tapeworm. 
Life history.—The life history of these tapeworms is not known. 
Sheep are herbivorous animals and would only by accident eat ani- 
mals, such as insects, that might serve as intermediate hosts. It is 
probable that the intermediate hosts are small animals, such as 
insects, that are taken in by the sheep on grass, but we have no evi- 
dence on this subject. 
8’ Moniezia erpansa, M. trigonophora, and M. planissima. 
~ Tory 
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