1911] 



on Grouse Disease, 



21 



of the grouse chick to provide nourishment for the parasites, and, on 

 the other hand, to the multipUcative capacity of the parasites them- 

 selves. The Goccidium then l)egins to reproduce sexually. Many 

 small male parasites are produced, together with larger food-con- 

 taining female Coccidia. The male and female parasites conjugate 

 and then encyst, bursting through into the cavity of the gut and 

 giving rise to the spores found in the cascal droppings on the moors. 

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

 cysts means either recovery or death. If the infection of the parasites 

 has been a heavy one, and multiplication of the parasites has proceeded 

 apace, then the destruction of the intestinal epithelium has been so 

 great that death of the grouse chick results. If, on the other hand, 

 the epithelium of the intestinal wall has not been too much destroyed 



Pig. 3. — Small piece of the epithelial lining of the gut of an infected grouse 

 chick, showing various stages in the life-history of Eimeria {Goccidium) 

 avium, parasites of different ages being present. 



par, parasite ; spz, sporozoite or primary infecting germ ; ;sc/j,"schizont 

 or dividing form ; mz, merozoite or daughter germ : ? , female Goccidium : 

 i , male parasite ; ooc, mature female, ready for fertilization, with oocyst 

 wall formed round it. 



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

 epithelium may slowly regenerate, and the young bird gradually 

 recover and improve in condition, after the Coccidian spores have 

 been passed out with the csecal 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 external symptom of the 



