232 



ZOOLOGY 



Life history 

 of the 

 tapeworm 



entirely different from that of an annelid or arthropod, 

 in which the successive segments carry different organs 

 and together make up a 

 single animal of which 

 they are the necessary 

 parts. In the tapeworm 

 the segments in a sense 

 represent different indi- 

 viduals, attached but not 

 combining to form parts 

 of a single machine. Each 

 segment takes nourish- 

 ment independently, 

 through the skin, and each 

 one produces eggs when 

 mature, excepting only the 

 "head" or scolex. 



The eggs give rise to a 

 hooked embryo (or in 

 some species to a ciliated 

 larva), which seeks the 

 proper host and develops 

 into a bladder worm or 

 Cysticercus. The host of 

 the Cysticercus is usually 



, , f. . . . FIG. 57. A tapeworm, Tania soliiim: 



eaten by the tinal host, in a> head . b> a prog i ttid; B, a single 



the body of which the ma- proglottid detached; p, genital pore; u, 



i 1 uterus. 



ture tapeworms develop. 



The invention of cooking by man not only made many 



substances palatable and digestible, but was of great 



importance as a means of destroying the young stages 



of parasitic worms, which would otherwise be eaten 



alive. 



From Nicholson's "Classification 

 of the Animal Kingdom" 



