PARASITOLOGY. 185 



Taenia Echinococcus (Kokkus — berry). 



Distributio7i. — One of the most common tapeworms 

 of dog's 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 booklets; 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. 

 It is four or five times as long as wide. As soon as 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 o^zz 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- 



