VERMES 



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in addition with a circle of hooks, and thus the scolex may be 

 pretty firmly attached to the wall of the intestine of the host. 

 Beginning a short distance back of the scolex, the entire tape- 

 worm is divided into parts or segments, usually very numerous, 

 which are very minute near the head and increase in length and 

 breadth toward the posterior end. 

 These segments, known techni- 

 cally as proglottides, are greatly 

 flattened, and each proglottis bears 

 typically, either on one of its flat- 

 tened surfaces or on one of its 

 margins, a single pore, which is 

 the genital opening common to 

 the male and female reproductive 

 apparatus ; the Cestoda are all 

 hermaphroditic. New proglottides 

 are constantly formed by trans- 

 verse divisions just back of the 

 scolex, and as they increase in 

 size are carried farther and farther 

 away from the head, while the seg- 

 ments at the free end of the worm 

 on reaching maturity separate from 

 the rest and pass out of the body 

 of the host. Each proglottis con- 

 tains the same organs as every 

 other proglottis, differing only in 

 the degree of development ; each 

 possesses the same muscular sys- 

 tem, the same rudimentary nervous 

 system, and the same system of Flc " L j 03 . Bothriocephalic lotus, the fish 



reproductive Organs. Further, tapeworm; portions from different 



parts of the colony. (After Leuckart.) 



when mature and separated from 



the others, each proglottis exhibits for a time the power of 

 independent motion, and may crawl about after leaving its host, 

 for some distance. These facts have led many zoologists to con- 

 sider the tapeworm as a colony of similar individuals placed end 

 to end. 



On the other hand, the scolex is decidedly different from the 



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