PARASITES OF ANIMALS. TT 
pork, is fully explained. Since these facts have been ascer- 
tained, search has been made for “measles” in beef from 
animals not experimented upon, and they have been found in 
several instances. 
When such beef is swallowed by man, without cooking, the 
young tape-worms are liberated from their capsules or cysts 
by the process of digestion ; the head becomes protruded, and, 
passing into the intestine, it fastens upon the lining mem- 
brane by its suckers. There it rapidly grows larger, new 
joints are developed, and the body grows longer and longer, 
the form of the joints changing as they grow, until those that 
are most mature become square, and finally oblong, as shown 
in Figure 57, which represents a beef tape-worm, of natural 
size, in several sections, the intermediate joints being omitted. 
When full grown, which requires three or four months, one of 
these tape-worms may contain over 800 joints, of which 3860 
to 400 of the last ones will be sexually mature, cach one con- 
taining 5000 or more eggs. This species is much larger than 
the pork tape-worm (T. solium), as well as longer, its length 
being sometimes twenty feet, and its greatest breadth half an 
inch, while the joints are thicker and stouter, or have a plump 
look, instead of being thin and flat, as in the other. The 
head, as already intimated, is quite different in the two species 
—that of the beef&worm being larger and flat, or even concave, — 
at the end, with four large suckers on the sides, as shown, 
greatly magnified, in Figure 58. The joints themselves are 
very different internally, the egg-masses or uteri being very 
numerous, and crowded together in a more parallel manner 
(Figure 59) in this than in the pork tape-worm, in which 
they are fewer and more aborescenfly branched. The mature 
joints, filled with eggs, are cast off, as in other tape-worms, 
and leaving the intestine, have an independent existence for 
a few days, when they burst by the enlargement of the embryos 
in the eggs. The eggs are thus scattered about in manure, in 
water, in the drainage of cess-pools and sewers, by the winds, 
and by insects. Itis not strange, therefore, that cattle should 
occasionally swallow such eggs with their food and drink, 
especially if we reflect that one man, harboring only one of 
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