718 UR. II. B. FAXTUAM OX AVIAN' COCCIDIOSIS. [IVfay 3. 



ilirs oxaniiiu'd r.iivly showed spores, but as they proceed almost at 

 once to ingest fa'ces, tliey rapidly become agents for (bstri})ntiiig the 

 spores. ])ung-fiies alloweil to liatcb out in the fa^-es of infected 

 grouse always contjiint'd c-occ-idian oocysts in their alinientaiy 

 canal and fa'ces. 



Laboratory expei'iments were made with the blow-fly, Mxisca 

 rowiioria. Eggs taken from the body of the parent fly were 

 allowed to hatch out in faeces of an infected grouse chick. The 

 larva^ greedily ingested the cysts which passed pi^actically unaltered 

 tluixigh their bodies. Some of the larva? which pupated were 

 waslietl very carefully and then dissected. They contained 

 coccidian spores. Adults were fed on the infected mateiial and 

 oocysts were voided in their excrement. The spreading of 

 young flies, hatched infected, and of older ones that have fed on 

 infected material, may aid, then, in the disper.sal of coccidiosis. 



While expei-imental evidence of the action of Scatophaya sier- 

 coraria and Musca vomitoria has been afforded in the laboratory, 

 this is merely confirmatoiy of what may occur on some moors. 

 Here on Scots firs, heather and moss, numbers of flies are 

 found, and dung-flies are known wherever grouse droppings are 

 to be found. The trail of birds can be tracked to some extent by 

 the coprophagous flies, while lines of infection are pi-oduced by the 

 birds as they j)ass down by small paths to their drinking places. 



It may be of interest to note that houseflies {Masca domestica) 

 have been shown experimentally to ingest coccidian oocysts. 



To sumniai'ise, wind and rain acting on infected fivces are 

 probably the princi})nl agents in dispersal, while the feeding habits 

 of HcaUrpluuja and other Hies form subsidiary means of spreading 

 the disease. 



VII. DURATIOX OF VlTAUTV OF COCCIDIAX OoCVSTS. 



(a) When the Oocysts are kept in water or very moist. 



Much moisture is present on many moors, and fa-ces of infected 

 chicks contain coccidian spores which not only get washed into 

 the soil, but also into tarns, etc., at which grouse drink. It was, 

 therefoi-e, of some importance to determine the time required 

 for the degeneration of the resistant s[)ores of the paiasite when 

 in watei'. 



Coccidian oocysts witli undifl'ereutiated contents were placed in 

 water, kept at al)Out, 20° C. (July tempeiature), the water being 

 replaced as requii-ed, to avoid evaporation eft'ects. Ordinarily, the 

 oocysts develop sporocysts very lapidly — in 2 to 8 days. In 

 the ca.se of cysts kept in water, 9 days elapsed before much 

 change was noted. At the end of that jeriod, a few oocysts 

 showed differentiated protoplasmic masses, and still fewer showed 

 foui- sporoc3'sts. Two days later many more oiicysts contained 

 fo!U' sporocysts, and this progi-essive development continued for 

 .some days. Little signs of degenerati(m were seen until about the 

 4()T.h day, when some .showed signs of gas bubbles in their interiors. 

 Others, however, lia<l completed their develoi>ment, and their four 



