GROUSE DISEASE 207 



diarrhoea, which usually terminates fatally. Grouse- 

 chicks are most susceptible to coccidiosis during 

 the first six weeks of their life, and if they can 

 survive this period unattacked, they usually 

 reach adult life. 



The disease we may call it Coccidiosis for 

 short caused by this species of Coccidium 

 is brought about in this way. The grouse 

 moor is simply peppered over with millions of 

 oval cysts, or capsules, which represent the free- 

 living stage in the life-history of the Coccidium. 

 Each cyst is very resistant to changes of tem- 

 perature and moisture, and can live for a long 

 time. The cysts pass with the food or the 

 water or the grit into the alimentary canal of 

 the bird, and in the duodenum the thick cyst 

 wall is dissolved and four spores emerge. Now, 

 when one reflects on the thousands of cysts 

 which are at times taken up by the grouse, one 

 can readily understand that the presence of these 

 numerous spores boring into the epithelial cells 

 ultimately destroys the lining of the duodenum, 

 where in fact the most active digestive processes 

 are carried on in the normal bird. Furthermore, 

 the Coccidia multiply in the intestine, and the 

 resulting progeny attack new regions of the 



