GROUSE DISEASE 211 



symptom of the disease is diarrhoea, the legs 

 show weakness, and the feathers, especially 

 around the legs, are in poor condition, flight is 

 feeble, and the bird loses weight. Internally the 

 alimentary canal is inflamed and digestion greatly 

 impaired ; perityphlitis is set up around the 

 caeca, which becomes greatly enlarged. The blood 

 corpuscles also undergo marked alteration, and 

 an anaemic condition prevails. Further, the de- 

 struction 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 de- 

 struction 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 (coccidium) avium, 



