IS Mr. Arthur E. Shipley [Feb. 3, 



Coccidmm is a protozoan, an animal with, as we shall see, a verv 

 complicated life-historj. 



Dealing first with the Coccidiosis : 



One of the aims of grouse-preservers is to have numbers of healthy 

 young grouse chicks in order to produce stocks of strong birds. 

 Bad seasons for grouse are partly due to epizootics among the young 

 In'oods in the spring, and the chief cause of mortahty among the 

 grouse chicks is a small, one-celled microscopic animal parasite, 

 Eimeria {Coccidium) avium. This parasite penetrates the lining 

 membrane of the gut of the bird and gradually destroys it, thereby 

 setting up digestive troubles in the form of intestinal inflammation 

 (enteritis), accompanied by acute diarrhoea, which usually terminates 

 fatally. Grouse chicks are most susceptible to Coccidiosis during 

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

 unattacked they usually reach adult hfe. 



The disease — we may call it Coccidiosis for short — caused by this 

 species of Coccidium {Eimeria avium) is brought about in this way. 

 The grouse moor is simply peppered over with millions of oval cysts, 

 or capsules, which represent the free-hving stage in the life-history 

 of the Coccidium. Each cyst is very resistant to changes of tempera- 

 ture 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 ])oring into 

 the epithelial cells ultimately destroys the lining of the duodenum, 

 where in fact the most active digestive processes are carried on in 

 the normal l)ird. Furthermore, the Coccidia multiply in the intestine, 

 and the resulting progeny attack new regions of the alimentary tract, 

 especially the cseca, 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 comphcated life-history of this parasite, which has 

 been worked out in the grouse by Dr. Fantham at Cambridge ; but 

 enough has been said to show the nature of the disease, which is well 

 known to occur in several other animals. There is a Coccidiosis of 

 the rabbit, and a very fatal form attacks pigeons, fowls and pheasants, 

 and the grouse Coccidium, if administered to chickens, will set up the 

 disease in fowls. 



To repeat a little, for the life-history of this parasite is very com- 

 plicated. 



The chief source of contamination on the moors is the droppings 

 of other diseased grouse. The droppings contain thousands of cysts 

 (oocysts) or spores of the parasite, and these spores, with their hard 



