94 BOARD OF ‘AGRICULTURE. 
branes. As long as these cysts remain in a living animal, 
new heads are constantly formed, by their peculiar methods 
of budding, and when new cysts are formed either within or 
outside of the older ones, they develop on their inner mem- 
branes other heads in the same way, so that if the sheep or 
other animal lives long enough to develop a large tumor, it will 
finally contain many thousands of these minute tape-worm 
heads. In examining one of these tumors taken from a dead 
animal, most of the heads and also the internal secondary cysts . 
are usually found floating freely in the watery fluid in great 
numbers, giving it a turbid appearance, and on standing they 
settle to the bottom as a granular sediment. This is 
due to changes after the death of the parasite, though some 
of the secondary cysts may be free during life. 
Development. 
Now, if a dog eats the liver, lungs, kidney, or other parts 
containing such tumors, and swallows either the cysts or the 
detached heads, these will lose the enclosing membrane, stems, 
and other parts that are no longer useful, the heads with their 
suckers and hooks will be. protruded, and, passing into the 
dog’s intestine, each one will fasten itself by means of the 
hooks and suckers to the soft membrane lining the intestine. 
In this situation they remain and soon develop a small body, 
having only three separable sexual joints, as shown in Figure 
70, which represents the mature tape-worm (Tenia echinococ- 
cus) greatly magnified. This tape-worm never becomes long, 
with hundreds of joints, as do the pork and beef tape-worms of 
man. It is only about an eighth of an inch long when ma- 
ture. The last joint, which is much the largest, contains both 
male and female organs, and is perhaps capable of self-impreg- 
nation ; itis therefore a complete hermaphrodite. Afterthis 
has matured and discharged its eggs, the two next in turn de- 
velop their sexual organs and take its place. In Figure 70- 
the male organ may be seen projecting from one side, and the 
ovaries, containing many eggs, occupy the bulk of the 
joint. The eggs pass out through a. duct that opens by 
the side of the male organ, and each egg is fertilized 
before being discharged. Thousands of these little tape- 
worms, derived from6tie°laygéeystP often live together in 
