CHAPTER IX 



" GROUSE DISEASE " CONTINUED COCCIDIOSIS 



REFERENCE has already been made to the circumstance that 

 in certain years there is a mysterious disappearance of the 

 young birds even though the old birds appear to be healthy, 

 and the weather conditions ideal. 



At first it appeared probable that this failure of the young 

 stock was due to some climatic cause, such as wet or drought, 

 or to the failure of some essential element in the food supply. 

 As the subject was further investigated, however, it was seen 

 that none of these explanations were satisfactory, and the 

 matter remained in doubt until it was discovered that the 

 mortality in question was the result of a definite disease which 

 more particularly affected the young birds, and which had 

 hitherto been overlooked. 



In the course of investigating Strongylosis in Grouse on the 

 moors in May 1909, it was noticed that the cysts of a Coccidium 

 a minute animal parasite often occurred in large numbers in 

 the gut of Grouse chicks. These coccidian cysts are oval (see 

 Fig. 35), and at first sight might easily be mistaken for eggs 

 of worms, though they are somewhat smaller. The presence of 

 the cysts was often associated with enteritis in many cases with 

 fatal results. The discovery suggested that Coccidiosis was a 

 factor in " Grouse Disease," especially in young birds. It is 

 true that the occurrence of coccidian cysts had been observed 

 in adult Grouse at various times, but not in large numbers, and 

 there is no evidence that their presence in adult birds is 

 attended with fatal results in any but exceptional cases. 



With a view to further investigation of this disease, Dr 

 Fantham, in June 1909, spent some time upon a Grouse moor 

 in Scotland, and the results of his researches there, and after- 



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