572 SCIENCE PROGRESS 



number of Hemipterous insects resembling the frog- or cuckoo- 

 spit, a fly, two specimens of plant-lice, one small spider, and the 

 remains of four slugs. The gizzard of the same animal con- 

 tained, in a more broken-up condition, two or three dozen larva 

 of saw-flies and moths, some young Hemipterous insects and 

 the pupa of two true flies. 



In searching for the larval or cysticercus stage of these and 

 the other cestodes, we have examined a considerable number 

 of insects which occur commonly on grouse moors. We have 

 also carefully searched the bodies of many fresh-water Crustacea 

 which abound in the pools and tarns from which grouse drink 

 but hitherto our searches have met with no success. One 

 specimen of cestode which infests the common fowl is said 

 to have its second host in several species of the slug Limax 

 but we have not succeeded in finding cysts of either form of 

 tape-worm in this slug. 



But besides the large tape-worm {Davainea ttrogalli), which 

 was described by Baird fifty-seven years ago and the thread- or 

 round-worm {Trichostrongylus pergracilis), described by Cobbold 

 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 {Hymcnolepis 

 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 contents of the alimentary canal in this region 

 resemble a thick puree, which, on the addition of some fixing 

 reagent, resolves itself into an inextricable tangle of fine threads, 

 each representing a tape-worm. The head of these worms is 

 hidden away in the folds of the lining mucous membrane of the 

 alimentary canal and undoubtedly they do something to interfere 

 with its continuity. A certain amount of inflammation 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 Hymcnolepis 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 recently been found in a flea by Professor Minchin 

 and these cysts have been shown by Mr. Nicoll to grow into 

 Hymcnolepis diminuta in the intestine of the rat. Hence the 

 suggestion, first made by Dr. Leiper, that the fleas of the 



