204 STUDIES IN INSECT LIFE, ETC. 



(Trichostrongylus pergracilis) , described by Cob- 

 bold thirty-seven years ago, we have two other 

 species of tape-worm and four other species of 

 round-worm. One of the former is negligible, 

 the other, the transparent tape-worm (Hyme- 

 nolepis microps), is however to some extent 

 associated with disease. These worms, like the 

 larger species, may exist in incredible numbers 

 in the duodenum or that part of the alimentary 

 canal which comes just after the gizzard ; yet 

 they are quite invisible whilst alive. The con- 

 tents of the alimentary canal in this region re- 

 semble a thick puree, which, on the addition of 

 some fixing reagent, resolves itself into an in- 

 extricable tangle of fine threads, each repre- 

 senting a tape-worm. The heads of these worms 

 are hidden away in the folds of the lining mucous 

 membrane of the alimentary canal, and un- 

 doubtedly they do something to interfere with 

 its continuity. A certain amount of inflamma- 

 tion is set up. We have no sure information 

 as to the second host of this cestode, but as a 

 general rule the cysts of the genus Hymenolepis 

 live in some insect or centipede, as is shown by 

 the fact that the adults exist in bats, insectivores, 

 and insectivorous birds. Tape-worm cysts have 



