"GROUSE DISEASE"— COCCIDIOSIS 253 



chicks were collected each morning, for these soft droppings are more abundant 

 during the night than they are during the day, and in the early morning there is a 

 better chance of obtaining excrement free from soil. Examination of faeces collected 

 in the evening was sometimes made. 



The Grouse chicks were kept on the experimental ground at Frimley, and the 

 feeding experiments were conducted by Dr E. A. Wilson. Samples of the freces of 

 the birds were sent to me daily. 



(B) Fowl Chicks and Young Pigeons. — A method of feeding similar to that 

 used for Grouse chicks was employed with fowl chicks and young pigeons (squabs). 

 These experiments were conducted by me at Cambridge. The chicks used were 

 from incubated eggs, the eggs having been carefully cleansed antiseptically before 

 incubation. Ccecal droppings containing oocysts were administered directly to the 

 Ijirds. Very small daily doses were used for several days and then none for a 

 couple of days, and so on. This method of administering oocysts was quite efiective, 

 and had the advantage of reproducing somewhat the condition of wild Grouse on the 

 moors, where intermittent ingestion of oocysts with food or drink occurs. 



One experiment was performed in which a single dose only had a fatal effect on 

 a fowl chick. 



Droppings containing oocysts in different stages of development (Figs. 4-7) 

 were also used. When the oocysts contained developed sporocysts the onset of 

 Coccidiosis was more rapid. 



Again, I have found coccidian oocysts in the water of tarns at which Grouse 

 chicks drink and also in dew collected from the heather on the moors (Fig. 8). 

 Grouse chicks, then, can acquire coccidian oocysts by way of their drink. To show 

 this method of infection experimentally, a healthy fowl chick was supplied with 

 water containing coccidian oocysts. This bird also became infected with 

 Coccidiosis. 



Control birds were most carefully kept. These were supplied with food and 

 drink exactly as were the treated birds, and kept under the same conditions. 

 Examination of their faeces was made twice daily, and careful search was made for 

 oocysts as the possibility of natural Coccidiosis of both fowls and pigeons ' was well 

 recognised and most carefully guarded against. Control birds were invariably 

 healthy, and made more rapid progress in growth than did the subjects of the 

 experiment. 



' Through the courtesy of a friend I was able to examine coccidian oocysts from a pigeon suffering from 

 natural Coccidiosis. On PI. xxxviii., Fig. 13 is drawn a cyst of this Coccidium (C. pfeifferi oi Lahhe). It 

 is spherical, about 17m iu diameter. 



