PARASITOLOGY. 185 
TAENIA Ecuinococcus (Kokkus—berry). 
Distribution.—One of the most common tapeworms 
of dogs in the United States. In autopsy of eighty 
dogs fifty percent were found to be infested by the 
Taenia Echinococcus; also found in Europe On an 
average about one percent of hogs harbor the cystic 
form; rare in sheep; not reported in cattle in this 
country. 
Description.—The head of the adult worm is glob- 
ular in shape, provided with four sucker discs and a 
rostellum of from twenty-eight to fifty hooklets; the 
neck is long and distinct; the entire worm consists 
of four segments, including the head; the terminal 
segment is nearly as long as the balance of the worm. 
Itis four or five times as long as wide. Assoonas the 
segment is ripe (filled with mature ova) it detaches 
itself, and is passed out to the ground with the feces. 
The entire worm measures from one-fifth to one- 
fourth inch long and is very slender; as a result it 
may be easily overlooked in holding autopsy. 
Life History.—The intermediate host is the hog, 
sheep, ox or man. The detached segment, which 
passes to the ground, soon decays and liberates 
myriads of ova, which become disseminated over 
the ground, pasture and water supply by the rains; 
thus through contaminated water and food this 
microscopic egg is taken in by the intermediate host. 
Upon reaching the stomach a minute six-hooked 
embryo is liberated which invades the tissues and 
becomes lodged in some organ, usually the liver or 
lungs; it here undergoes a metamorphosis into the 
larval form. First is developed an acephalocyst ; 
this is provided with hydatic and germinal mem- 
