110 BOARD OF AGRICULTURE. 
diameter of one-eighth to one-fifth of an inch. The females 
may become six inches, or even a foot in length, and some- 
times one-quarter of an inch in diameter, though generally: 
Figure 74. 
" smaller. The female is very prolific, producing an immense 
number of somewhat oblong-oval eggs. 
The history of its development and transformations has 
not yet been made out. There can be little or no doubt, 
however, that the young worms are parasitic in some other 
animals,—most likely in insects, worms, or ‘snails,—and that 
the hogs get them by devouring the embryos included in 
some such small animals. : 
Effects and Symptoms. 
This is the commonest and most injurious intestinal worm 
found in swine. These parasites live in the small intestine, 
and more rarely in the large intestine. They usually adhere 
to the lining, or mucus membrane, by means Figure 75. 
of the hooks on the proboscis, which is thrust Be 
into the substance of the membrane. Not 
unfrequently they perforate the walls of the 
intestine and stray into other parts of the 
viscera, producing serious disease. Some- 
times the intestine of ‘a hog is found per- 
forated by so many of these holes that it can- 
not be used in the manufacture of sausages ! 
In severe cases, hogs afflicted with this parasite are weak 
in the loins, and have the membranes in the corners of the 
eyes swollen, watery, and lighter colored than usual. The 
excrement is hardened and highly colored, and the animal 
often keeps up a continual squealing and grunting, especially 
in the morning. Such hogs are generally cross and morose, 
Figure 74.—Echinorhynchus gigas, natural size. From Cuvier. 
Figure 75.—Head of Z. gigas, enlarged showing the reticulated vessels in th 
skin. From Cuvier, é 
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