T^ENIA SAGINATA GOEZE 



73 



not uncommon and cases have been reported where the worm at- 

 tained the considerable length of thirty-six metres. As the body 

 of the worm is very contractile the length is subject to great 

 variations even if the age and number of proglottids is the same. 

 The scolex (unfortunately often called "head") is at the fore- 

 most end of the body 

 and is followed by a 

 long strobila or chain of 

 upwards of one thou- 

 sand proglottids which 

 increase gradually in 

 length and width. The 

 oldest proglottids are 

 at the posterior end of 

 the worm. Daily sev- 

 eral of these proglot- 

 tids break off and leave 

 the intestine of the pa- 

 t i e n t spontaneously, 

 and daily new proglot- 

 tids are formed by the 

 scolex by a process of 

 strobilization or seg- 

 mentation of its 

 "neck." If the entire 

 chain is broken off at 

 the scolex, it takes the 

 latter from ten to 

 twelve weeks to pro- 

 duce a new chain. The internal organization of each proglot- 

 tid is the same as that of the preceding and following pro- 

 glottids, but sexual mature proglottids are found only, roughly 

 speaking, in the middle third of the chain. The posterior 

 proglottids show a degeneration of the sexual organs owing to 

 the enormous development of the uterus under pressure of the 



L1\L 



VN 



FIG. 1 6. Nervous system in the scolex of 

 Tania ccenurus after Niemiec. DN, dorsal 

 nerve; LN, lateral nerve; VN, ventral nerve. 



