194 THE GROUSE IN HEALTH AND IN DISEASE 



The numbers were, however, meagre and tow-nettings later 

 in the summer yielded an even more unsatisfactory " bag." 

 None of the Crustacea 1 when examined microscopically showed 

 any cysts, and as they are few in number it seems improbable 

 that the source of the tapeworm infection lies here. 



We have thus with some degree of probability shut out as 

 second or larval host of the tapeworms at any rate for the 

 present the ectoparasites of the Grouse, the myriapoda and 

 the slugs or snails and fresh-water Crustacea, and this on the 

 grounds (1) that on examination none of them reveal a cyst, 

 and (2) that these animals are either not eaten by the bird, or 

 so rarely eaten and in quantities so small as to render it highly 

 improbable that any of these invertebrates could account for 

 the almost constant presence of the tapeworms in large numbers 

 in the Grouse. 



Two rather striking facts seem to point to the normal insect 

 food of the Grouse, which it picks up on the moor, as the more 

 probable source of tapeworms. One is that two artificially 

 reared Grouse which died during the early autumn of 1907, 

 when carefully searched for tapeworms were found to be entirely 

 free from them. The second fact is, that under natural con- 

 ditions young Grouse often contain fully grown " large " tape- 

 worms (Davainea) before they are three weeks old. They 

 must certainly have swallowed the second host when very 

 young, perhaps even the day they were hatched, or the worm 

 would not have had time to grow. The young birds live very 

 largely on an insect diet. Hence the best chance of finding this 

 second host is to examine the crop contents of the very young 

 birds, and to do this the observer must have a moor at his dis- 

 posal, with leave to kill as many young birds as he may want, 

 and this is a very difficult thing to obtain. 



It has been stated over and over again by sportsmen and 

 gamekeepers that the Grouse eats no insects, but this is far 

 from the truth. 



1 A fuller report on the insects found in the Grouse-crop has been given by Mr 

 J. C. F. Fryer. 



