100 



THE TAPEWORM 



structures, adapted for holding fast to the host, are found upon the 

 scolex? Count the proglottids, compare with numbers in neighboring 

 specimens, and record. How and where do the proglottids seem to 

 originate? If living worms are available, test the firmness of their 

 attachment to the mucous membrane of the host. Why is it important 

 that this attachment be maintained? Compare the external features 

 of Tsenia with those of other tapeworms, such as Moniezia expansa, 

 from the sheep, and Crossohothrium laciniatum, from the sand-shark, 

 that may be available as demonstration specimens. Draw figures 

 (X 15-20) of the scolex and representative stages in the development 

 of proglottids. 



uterus 



cfuctus 

 effenens 



teeth 



yductus deferens 



y pen 15 

 - gen/tol pore 



sem/'na/ receptac/e 



^ - yofJ< ^hncf 



Fig. 49. — A proglottid of ;i cestodo, slunving the reproductive system; 



diagranunatic. 



Exercise 2. — Internal Structure of a Proglottid. 



(c) Mature proglottids of Tsenia, Crossohothrium laciniatum, or 

 other favorable material stained to show the internal structure, will 

 be provided and cxj^lained as necessary by the instructor. Recognize 

 the nerve cords, excretory ducts, ]>arts of the reproductive system. 



