578 SCIENCE PROGRESS 



the destruction of the lining wall of the alimentary tract allows 

 the escape of bacteria which are all very well in their place 

 — i.e. the cavity of the intestine — but which are apt to set up 

 trouble when they make their way into other tissues. This 

 is however but a subsidiary matter ; the real injury caused 

 by the Coccidium is the destruction of the lining membrane of 

 the alimentary canal. 



Coccidiosis may be spread from moor to moor by the 

 agency of flies. The maggots of certain flies readily eat the 

 cysts, and it has been shown both experimentally and on 

 the moor that the cysts pass through the bodies of both maggot 

 and fly undigested and unharmed. 



Several other one-celled microscopic organisms or protozoa, 

 besides Eimeria {Coccidiuni) avmm^ as is mentioned above, have 

 been found in the intestines of grouse and also in their blood, 

 but in no case, so far, has any of these parasites been shown to 

 have a markedly dangerous effect on the bird harbouring it. 

 Some of these parasites, in fact, occur in perfectly healthy 

 grouse and apparently are almost innocuous. 



Strongylosis 



The second disease which the Inquiry has found responsible 

 for grouse epizootics observed between 1905 and 1910 is one to 

 which Cobbold drew attention in 1873, though he attempted 

 little in the way of pathological investigation. According to 

 him it is caused by the presence of a round-worm, now known 

 as Trichostrongylus pergracilis, in the caeca. We may call the 

 disease " Strongylosis of the grouse." The worms are minute, 

 transparent, very slender, a little less than half an inch in 

 length and they may exist in enormous numbers, 10,000 

 occurring in the two caeca of one bird. They are about 

 equally divided between the two blind-guts. We may recall 

 the fact that in the grouse the caeca are of unusual size and 

 that in these birds the digested food is absorbed in this region 

 of the alimentary canal alone. 



The worms seem to be most numerous at the proximal end 

 of the caeca, and when they exist in large numbers the contents 

 of these most important diverticula of the alimentary canal 

 become hard and very adherent to the mucous membrane, 

 forming whitish patches when seen from the outside. After 



