256 THE GROUSE IN HEALTH AND IN DISEASE 



the oocyst is determined by the space in the cell available for 

 the development of the macrogamete and by the numbers of the 

 parasite present. Where many parasites are aggregated together 

 in a limited area the macrogametes and oocysts are small, while 

 in areas of the gut which are but slightly parasitised large 

 oocysts preponderate. Nutrition of the parasite has obviously 

 a great influence on both its size and its propagative power. 

 In some cases the gut- wall becomes extremely thin and tender; 

 in other birds this is not so marked. Inflammatory patches 

 may be seen at intervals, particularly in the caeca, and the 

 caeca are usually enlarged. 



The main intestine of chicks infected with Coccidiosis 

 sometimes shows inflammatory patches, and blood may be 

 present in the rectal contents. The rectum itself is rarely 

 attacked, though its contents usually contain oocysts. 



The kidneys, spleen, liver, and gall-bladder of the infected 

 birds examined have not been found to contain Coccidia, 

 though the liver and gall-bladder are sometimes enlarged. 



Examination of the generative organs has shown no trace 

 of the parasite, though it is possible that eggs may become 

 contaminated during their passage through the cloaca of the 

 mother. The young chicks then might be hatched in contact 

 with infected material, and so acquire Coccidiosis early in life. 



Effect on A reflex of Coccidiosis is seen in the blood of infected Grouse. 



od * Besides becoming anaemic, there is an alteration in the relative 

 numbers of the blood corpuscles, infected birds showing an 

 increase in the number of polymorphonuclear leucocytes. 



Coccidia and It has already been shown that many bacteria are naturally 

 present, mixed with the contents of the gut even of healthy 

 Grouse, and it might be thought that these bacteria would have 

 a harmful effect on the bird if they gained access to other parts 

 of its system. It has been proved that these bacteria may be 

 introduced into the tissues of the gut through the agency of the 

 Coccidium, the sporozoites, and merozoites acting, in fact, as 

 inoculating needles. Thus, the injurious bacteria may, by way 

 of the blood and lymph, reach other organs. The agency of 



