172 PARASITOLOGY. 



TAPEWORMS OF MAN. 



Two tapeworms of man find a lower animal as 

 an intermediate host, viz. : Taenia Solium and 

 Taenia Saginata, 



Taenia Solium (Taenia — ribbon) 

 (Sola — alone) 



Syiionym. — Taenia Armata. 



Histoiy. — Adult tapeworms in man and their effect 

 upon the health of the host dates back to the begin- 

 ning of history; we find the first description of tape- 

 worms in the seventeenth century. The life cycle 

 was worked out about 1850. 



Dist7'ibution. — Frequent in the United States ; also 

 found in many other countries. 



Descriptio7i. — The head is scarcely larger than a 

 pin head and is provided with four sucker discs and 

 twenty-four to thirty-tv;o booklets , The worm may 

 reach the length of forty feet. I'he latter segments 

 are as long or longer than broad ; the genital pores 

 are prominent and irregularly alternate ; as soon as 

 the segments are filled with mature ova they detach 

 themselves and pass out to the ground with the feces. 

 From one to half a dozen detach themselves at one 

 time. Each segment contains many hundred ova. 



Life Cycle. — The ova become disseminated 

 through the water or food and are through these 

 channels taken in by the intermediate host, which is 

 the hog. In the stomach the ovum hatches into a 

 six-hooked embryo, which, by means of its booklets 

 finds its way through the stomach or intestinal wall 

 and wanders through the tissues or is carried by the 

 blood stream or lymph current ; in nine days the em- 



