DWARF TAPE WORM 257 



of T. saginata are, however, much more powerful than those of T. solium. The 

 segments have only five to ten coarse branches and are expelled only at the time of 

 defecation. The segments or the ova having been ingested by a hog, the six-hooked 

 embryo is liberated and becomes encysted chiefly in the tongue, neck, and shoulder 

 muscles of the hog, as an invaginated scolex. Pork containing this cysticercus 

 (Cysticercus cellulosae) is known as measly pork. This cysticercus contains much 

 more fluid than that of the ox and is from 1/4 to 4/5 of an inch long. If one by 

 chance should carry the egg on his fingers to his mouth, as the result of examining 

 mature segments, the larval stage may be established in man. If this infection is 

 not heavy, very few symptoms may be observed. The cysticercus, however, tends 

 to invade the brain, next in frequency the eye, and so causes convulsions, death or 

 blindness. Instead of only being the size of a pea, these cysts, when forming in the 

 brain, may be the size of a walnut or larger. T. solium is comparatively common in 

 North Germany, but is exceedingly rare in England and the United States. 



Taenia africana. This is an unarmed tape-worm, only about 5 feet long. It 

 was found in a native soldier in German East Africa. - 



Garrison has reported from the Philippines a tape-worm with an unarmed 

 rostellum, V-shape and spiral formation of the uterine stem with compact structure 

 of the gravid uterus under the name of Taenia philippina. Another tape-worm, 

 T. confusa of which only segments were found was reported by Ward from Nebraska. 



Hymenolepis nana (Taenia nana). This is generally known as the 

 dwarf tape-worm -it is the smallest of the human tape-worms. It is 

 from 1/4 of an inch to 1/2 inch in length, and is less than 1/25 of an 

 inch in breadth. (zoX i m.m.) 



The genus Hymenolepis has lateral genital pores, all of which are on the same 

 side. These lateral genital pores cannot be made out in specimens as ordinarily 

 examined. The head has four suckers and a rostellum, which is usually invaginated. 

 The rostellum has a single row of twenty-four to thirty hooklets encircling it. Of 

 the 150 to 200 narrow segments the terminal ones are packed with eggs which in the 

 last two or three seem to fill entirely the disintegrating segments. It would seem 

 that the fully mature segments disintegrate and in this way the eggs are set free in 

 the surrounding intestinal contents. 



The worms as found in fresh faeces after taeniacide treatment are frequently in 

 an advanced state of disintegration so that it is impossible to make out the head or 

 hooklets. 



The eggs of this species are quite characteristic, there being two distinct mem- 

 branes. The inner one has two distinct knobs, from which thread-like filaments 

 proceed. The eggs of the H. diminuta have a thicker, striated, outer membrane 

 and there are no filaments. The eggs of the Dipylidium caninum are similar, but are 

 found in the faeces in aggregations several eggs in a packet. 



The dwarf tape-worm has been found to be the most common tape- 

 worm in the United States. Dr. Stiles found it in about 5% of children 

 in a Washington orphanage. 

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