"GROUSE DISEASE "—COCCIDIOSIS 257 



expected from the great emaciation and " bluish " appearance of the birds for 

 some days previous to the actual decease. 



All infected corpses should be burned, not buried. 



IV. Internal Organs. 



Detailed examination of diseased birds shows that Coccidiosis of fowls, pigeons, 

 and young Grouse is confined chiefly to the digestive tract, and so is unlike the 

 Coccidiosis of the rabbit, where both the liver and the gut may be affected. 



Dead chicks have shown oval coccidian oocysts (Text-Fig. 2, p. 258) in the 

 discharge from the nostrils. Scrapings from the soft palate, trachea, and oesophagus 

 of diseased birds have shown the presence of oocysts embedded in mucilage. 

 Possibly the oocysts may have regurgitated from the gizzard or intestine. Oocysts 

 are occasionally present in the crop and gizzard, mixed with crushed food, having 

 been probably taken up with the food. 



The intestine is more highly parasitised than any other part of the alimentary 

 tract. The oocysts (PI. xxxviii.. Figs. 7, 8, 11, 12), which show much variation 

 among themselves, are softened by the pancreatic juice, the four sporocysts 

 (Figs. 9, 10) emerge, and from each of them two active, motile sporozoites or germs 

 come out and proceed to attack the epithelium of the duodenum. Having 

 penetrated the epithelium (Fig. 1) they become round, grow and produce 

 individuals, destined to divide and give rise to a barrel-shaped mass of active 

 daughter germs, the merozoites (Fig. 1, mt). These merozoites separate from one 

 another and infect fresh epithelial cells, the whole mucous membrane being soon 

 badly infested, and becoming reduced to an almost structureless mass (Fig. 1). 

 Owing to heavy infection in the duodenal epithelium, death of the young Grouse 

 may occur. However, in many cases, some of the merozoites pass into the lumen 

 of the gut and reach the caeca, the tissues of which are similarly mutilated. As far 

 as my experiments go at present, the full period of schizogony would appear to be 

 from four to five days, as judged by the appearance and general moping of 

 the birds. 



After several generations of merozoites have been produced, the power of the 



host to provide food for the parasite fails, and consequent on this, the latter begins 



to make preparation for extra-corporeal life, and produces large, granular forms, 



which are female (mother) cells or macro-gametocytes (Fig. 1, ?) and somewhat 



smaller, less granular ones which are micro-gametocytes (Fig. 2, 6). Each macro- 



gametocyte gives rise to one passive macrogamete or female element (Fig. 1), while 

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