PARASITOLOGY. 173 
bryo finds a resting place. From this small mass ot 
protoplasm is developed first an acephalo cyst, 
which is provided with two membranes, the outer 
one called the hydatic membrane and the inner one 
called the germinal membrane; from the germinal 
membrane there is developed the larva; this consti- 
tutes the fully developed larval state. The cyst is 
oval in shape and about one-half to two-thirds the 
size of a navy bean; the larvacan be seen through 
the cyst wall as a small white body and consists of 
the head, provided with four sucker discs and twenty- 
four to thirty-two hooklets arranged in a double row. 
This head or larva is attached to the inner or ger- 
minal membrane by means of a pedicle and floats in 
a colorless fluid; each cyst contains but one larva. 
The cyst is fully developed in sixty days; it infests 
voluntary, involuntary and heart muscles, and the 
glands and organs of the body, invading the cancel- 
lated portion of bone. After cysts are quite old they 
undergo degeneration, beginning from without to 
within; through this degeneration process the cyst 
wall may rupture and and cyst collapse, or it may 
become filled with a cheesy or earthy material. 
Should man eat the meat of the hog infested with 
the cyst containing the living larva, through diges- 
tion the larva is liberated and finds its way to the 
small intestines and fixes itself to the mucous mem- 
brane by means of its hooklets and four sucker discs, 
and develops into the mature form. 
Animals Intested.—Man, hog and dog. 
Parts Infested. — Adult infests the small intestines 
of man. The larval form infest the muscle structure 
of the hog and sometimes the dog, in cyst formation. 
