"GROUSE DISEASE "—COCCIDIOSIS 237 



the law of priority in nomenclature is not only lawful but imperative " {Nature, 

 March 3rd, 1910). It would save much confusion if the question of zoological 

 nomenclature were settled by an international committee/ as has been suggested 

 by many able workers. 



The Coccidia of birds were first recorded in fowls by Silvestrini and Rivolta 

 (1873), under the name Psorospermium avium. Subsequently Railliet and Lucet 

 (1891) recorded Coccidia from fowls, naming the parasite Coccidium tenellum. 

 I have followed Doflein (1909) in naming the Coccidia of birds Eimeria avium. 

 The coccidian parasites were obtained from Grouse chicks, and I have succeeded 

 in transmitting the Coccidia of Grouse to fowl chicks and to young pigeons. 



III. Methods. 



In this investigation of Coccidiosis both fresh and preserved materials were 

 used. Samples of gut contents, taken from different regions, were examined fresh, 

 and often these have been fixed wet with osmic or formalin vapour, and stained by 

 Delafield's htematoxylin or by Giemsa's stain. Such smears were sometimes useful 

 for examining merozoites. 



Oocysts, because of the chitinoid and almost impenetrable character of their 

 walls, had to be examined fresh. 



For preserved material, the best fixatives were found to be Schaudinn's fluid 

 (corrosive-acetic-alcohol) and Bouin's fluid (picro-formol-acetic), to which a few 

 drops of absolute alcohol were added. Schaudinn's fluid tends to shrink the tissues, 

 while Bouin's fluid requires much washing out. Sections, 5^ to 6^ thick, were 

 made of the duodenum and csecum of infected birds, these parts of the digestive 

 tract being esj^ecially examined. The chief stains used were Delafield's heematoxylin 

 (either alone or counterstained with orange G or eosin), which was found to be 

 most useful, safranin and lichtgriin, iron-hasmatoxylin (with or without Van 

 Gieson's picro-fuchsin), and paracarmine. On the whole the heematoxylins proved 

 of most service. 



On diluting some of the csecal contents or faeces of a Grouse chick suSiering 

 from Coccidiosis, and examining the preparation microscopically, numerous oval 

 cysts are seen (PL xxxvii., Figs. 61-66). Sometimes the cysts are also Morpho- 

 seen in the small intestine just beyond the duodenum. These cysts may '°^y- 

 have homogeneous contents, or, when older, may show four more or less well 



' The subject of zoological nomenclature is now (1911) being so considered. 



