"GROUSE DISEASE " COCCIDIOS IS 251 



were derived from Coccidia in the oviduct of the mother, or perhaps from intestinal 

 Coccidia which had ascended by way of the cloaca. I think that cloacal conta- 

 mination was the more probable, for I have never seen Coccidia in the genitalia 

 of adult Grouse examined. 



A reflex of Coccidiosis is seen in the blood of infected birds, where polymor- 

 phonuclear leucocytosis is induced (vide chapter xiii. p. 315). 



Lesions caused by Coccidia in the mucous membrane may admit bacteria to the 

 circulation of the host (vide chapter xii. pp. 295 et seq.). Rettger (1909) believes 

 that " white diarrhoea " of fowls in America is due to a bacterium, while Morse 

 (1908) considers that it is primarily due to Coccidiosis. The discrepancy between 

 the results of these American workers is thus capable of explanation. 



VI. CONCLUDING REMARKS. 



Eimeria avium of Grouse is not restricted to this particular bird, for by 

 administering faeces containing oocysts from diseased Grouse to young fowl chicks 

 and pigeons, I have been able to reproduce the disease exactly as it occurs in Grouse 

 (p. 254). M'Fadyean (I89i) found Coccidiosis in pheasants, while "white 

 diarrhoea " of fowls has been the subject of much investigation, particularly recently 

 in America, where Morse (1908) and Hadley (1909) have worked on the subject. 

 Morse's account of preventive measures is very good, and he also notes Coccidiosis in 

 many other birds, but the figures of the complete life-cycle of the parasite are not 

 yet published. Labbe (1896) also has described Coccidiosis in certain marine birds. 



Though Coccidiosis is peculiarly fatal to Grouse chicks during the first few weeks 

 of their lives, adult Grouse also can become infected, for I have examined an adult 

 bird that probably died of Coccidiosis. Old birds in the chronic condition serve aa 

 reservoirs of oocysts and so may form sources of new infections on the moors. All 

 infected corpses should be burned, not buried. 



I may add that, while correcting the proofs of this memoir, I have been able to 

 examine pheasant chicks dying from Coccidiosis, the birds being obtained through 

 the courtesy of Drs Shipley and Hammond Smith from various parts of England 

 during June and July 1910. 



The economic importance of Coccidiosis in birds, especially in the young, is 

 evident, and I trust that this work, which to the best of my belief is the first fully 

 illustrated and detailed life-history of an Avian Coccidium, may draw more attention 

 to a subject both of great scientific interest and of practical importance. 



