210 STUDIES IN INSECT LIFE, ETC. 



hand to the multiplicative capacity of the para- 

 sites themselves. The Coccidium then begins to 

 reproduce sexually. Many small male parasites 

 are produced, together with larger food-containing 

 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 caecal droppings on the moors. 



So far as the grouse-chick is concerned, the 

 formation of Coccidian cysts means either re- 

 covery or death. If the infection of the parasites 

 has been a heavy one, and multiplication of the 

 parasite has proceeded apace, then the destruc- 

 tion 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 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 caecal droppings. 



As a rule, grouse are most susceptible to Cocci- 

 diosis 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 



