PARASITOLOGY. 175 



Description. — This worm is flat and ribbon shaped, 

 with a narrow neck of medium length joining the 

 head to the body ; the head is small and provided 

 with four sucker discs. It is the unarmed tapeworm 

 of man. The latter segments are a little longer than 

 broad ; the terminal segments are about three-six- 

 teenths of an inch wide ; the genital pores irregu- 

 larly alternate. The worm may reach the length of 

 forty feet. 



Life Cycle. — The life cycle is similar to that of the 

 Taenia Solium. The intermediate host is the ox, 

 which becomes infested through water or food contam- 

 inated with the infested excrements of man. The 

 ovum upon reaching the stomach of the ox is hatched 

 into a microscopic globular-shaped embryo provided 

 with six booklets. Like the embryo of the preceding 

 species they penetrate the tissues, through which they 

 gradually work their way to various parts of the 

 body, and in the course of nine days become station- 

 ary and they form a cyst through the same trans- 

 formation as in the preceding, which requires about 

 sixty days. These cvsts are about two-thirds the 

 size of a navy bean and contain a single larva which 

 consists of a head and neck. The head is provided 

 with four sucker discs ; by examining the cyst the 

 larva appears as a small white mass attached to the 

 mother or germinal membrane, floating in a color- 

 less fluid, and plainly visible through the cyst wall. 

 Should a member of the human family eat meat 

 (beef dried, rare done or raw,) containing the cysts 

 in which is found the living larva, he would become 

 infested with adult tapeworm. In the stomach the 

 larva would be liberated and upon reaching the 



