GROUSE DISEASE 



577 



So far as the grouse chick is concerned, the formation of 

 Coccidian cysts means either recovery or death. If the infec- 

 tion of the parasites has been a heavy one and multipHcation 

 of the parasite has proceeded apace, then the destruction of 

 the intestinal epithehum has been so great that death of the 

 grouse chick resuks. If, on the other hand, the epithehum of 

 the intestinal wall has not been too much destroyed — fewer 

 Coccidian parasites having been present — then the gut-epi- 

 thelium may slowly regenerate and the young bird gradually 



^spz. 



./•■■■■■'Vi 



par \^ „„.>-'"^' "'^'f *>v,/„ /^:"%w^ 



par m2 



Fig. 3. — Small piece of the epithelial Hning of the gut of an infected grouse chick, 

 showing various stages in the life-history of Eimeria {Coccidiut/i) avium, parasites of 

 different ages being present. 



J>ar, parasite ; spz, sporozoite or primary infecting germ ; sch, schizont or dividing form ; ?>iz, merozoite or 

 daughter germ ; ^ , female Coccidium ; jj , male parasite ; ode, mature female, ready for fertilisation, 

 with oocyst wall formed round it. 



recover and improve in condition after the Coccidian spores 

 have been passed out with the caecal droppings. 



As a rule grouse are most susceptible to Coccidiosis during 

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

 dangers of this period they usually grow up. The chief ex- 

 ternal 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 

 become greatly enlarged. The blood corpuscles also undergo 

 marked alteration and an anaemic condition prevails. Further, 



38 



