1911] on Grouse Disease. 17 



Besides the large tape-worm {Davainea urogalli), which \\as 

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

 worm {Trichostroigylus 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 {Hymenolepis 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 

 ((uite invisible wliilst 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 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 

 recently been found in a flea by Professor Minchin, and these cysts 

 have been shown by Mr. Nicoll to grow into Hymenolepis diminuta 

 in the intestine of the rat. Hence the suggestion, first made by 

 Dr. Leiper, that the fleas of the grouse may be the second host of 

 H. microps is well worth following up. 



It is curious to note that this tape-worm disappears during the 

 winter months, a fact which may afford some hint as to its second 

 host. The large tape-worms, on the other hand, remain all the year 

 round, and must be of quick growth, for they are found 85 cm. in 

 length in a young grouse but three weeks old. 



Three other round worms have also been shown to exist in the 

 grouse. One of these in the duodenum may prove of importance. 

 This species {Trichosoma longicolle) is allied to a form which lives in 

 the human appendix, and at times is the cause of appendicitis. 



COCCIDIOSIS. 



Besides the worms, we have in the grouse seven distinct uni- 

 cellular or protozoan parasites which live in the intestines or in the 

 blood of the grouse. Most of these are uncommon and comparatively 

 harmless, but one, a Goccidium (there is no more popular word for 

 it), is the cause of disease in the grouse chicks. 



Since this disease was first found in the young grouse much has 

 been written about it in the newspapers, and in nearly every case the 

 writer has taken the Goccidium to be a Goccus. Now a Goccus is no 

 more like a Goccidium than a crocus is like a crocodile. The Coccus 

 is a baclsrium, a vegetable, and it has a simple life-history ; the 



Vol. XX. (No. 105) c 



