FLAT WORMS 



(1) Genital pores single. Rostellum with not more than two rows of hooks, 

 (a) Suckers armed with numerous small booklets. Fifteen to twenty 



testicles in each segment. Davainea. 



(6) Suckers not armed. Three testicles in each segment. Hymeno- 

 lepsis. 



(2) Genital pores double. Rostellum with four or five rows of hooks. 



Dipylidium. 



TJENIID^E INFECTIONS 



Tsenia saginala (Taenia mediocanellata). This very widely dis- 

 tributed tape-worm is often termed the unarmed tape-worm, to 

 distinguish it from the T. solium or armed tape- worm. 



It is from 10 to 25 feet long and has several hundred proglottides. The small 

 pear-shaped head has four pigmented elliptical suckers and no booklets. The seg- 

 ments are plumper than those of T. solium, hence the name saginata. The single 

 lateral genital pore projects markedly and in a series of segments presents, as a rule, 

 first on one side, and then on the opposite side of the next segment (alternating). 

 The best way to distinguish a segment of the T. saginata from the T. solium is by 

 counting the number of lateral uterine branches; these number fifteen to thirty, are 

 quite delicate and branch dichotomously. The lateral divisions of the uterus of 

 the T. solium are tree-like in their branching and only number five to twelve on each 

 side. 



T. solium has three ovaries while T. saginata has only two. The ox is the inter- 

 mediate host of T. saginata. The eggs of Tcsnia have an oval outer shell which is 

 filled with rather translucent, refractile yolk, often in globules. Within the oval 

 shell is the more rounded cell of the six-hooked embryo with its thick striated 

 membrane. The outer shell is often absent in the eggs found in the faeces, only 

 the shell of the six-hooked embryo being found. The six-hooked embryo, having 

 worked, its way from the alimentary canal to the muscles or liver of the ox, 

 becomes encysted (Cysticercus bovis). This little bladder-like structure is about 

 Yi by y$ inch, and contains but a small amount of fluid. 



The evaginated head does not show booklets, they differing from the 

 armed rostellum of the scolex of Cysticercus cellulosce. 



Being ingested by man's eating raw or imperfectly cooked meat, the adult stage 

 becomes established in his alimentary canal in about two months. 



It is probable that the various raw-meat cures have made the infection more com- 

 mon. Cysticercus bovis is more abundant in the tongue of cattle than elsewhere in 

 the musculature. 



For this reason it would seem advisable to use other raw meat than beef in such 

 cures. 



In Abyssinia the infection is said to be universal, and a man without a tape- 

 worm to be a freak. An important point is the fact that the larval stage almost 

 never appears in man. It is this fact which makes it a so much less dangerous para- 

 site than the T. solium, which readily establishes a larval existence in man if the ova 



