GROUSE DISEASE 



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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 temperature 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 



D ^^I-/ E 



Fig. 2. — Oocysts (cysts) of Eimeria {Coccidium) avium. 



A, oocyst (cyst) with contents completely filling it ; b, oocyst with contents concentrated to form a central 

 mass ; c, commencement of division of the oocyst contents ; D, oocyst containing four rounded masses 

 that will become spores ; E, oocyst containing four sporocysts (spores) ; f, oocyst containing four sporo- 

 cysts, in each of which two sporozoites have formed. 



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 alimentary tract, especially the 

 caeca, which become swollen and inflamed. After a time some 

 of them produce small forms (males) and others change into 

 large forms (females) ; these two forms fuse and the resulting 

 stage is the cysts mentioned above, which, passing from the 

 body, infects the whole moor. There are many details omitted 

 in this short abstract of the complicated life-history of this 

 parasite, which have been worked out in the grouse by 



