1910.] UK. II U. FANTUAM OX AVIAX COCCIDIOSIS. 717 



for some weeks or some may become chronics, wlien ilaily 

 examination of their fajces shows periodic small crops of oocysts. 



Older chicks are more likely to recover from coccidiosis. J^'or 

 example, a grouse chick aged 13 weeks was fed on oocysts, and 

 when killed 3 weeks later very few coccidia were observed. 

 Again, a young grouse which had been picked up dead on the 

 moors in Invei^ness-shire was received on Sept. 15, 1909. In its 

 caeca numbers of both coccidian oocj'sts and Trlchostrougylus 

 pergracilis were found. The bird had probably survived an 

 attack of coccidiosis and in its weakened condition liad fallen 

 a victim to strongylosis. 



Different breeds of fowls have varying powers of resisting 

 coccidiosis. Pare-bred Leghorn and Minorca chicks died from 

 the disease in a comparatively short time< Plymouth Rock chicks 

 were attacked quickly but had greater resisting powers than pure 

 Leghorns or Minorcas, Cross-bred Leghorns were far more 

 resistant to the disease than the pure-bred birds. 



Regarding pigeons, fantails are more susceptible than the 

 ordinary pigeons, though squabs of any variety seem easily 

 attacked and overcome by coccidiosis. 



VI. The Disseminatiox of Coccidiosis over 

 Tracts of Couxtry. 



Coccidiosis outbreaks spread with fair rapidity, but though 

 many birds in one locality become diseased, yet adjoining estates 

 may be free. Epizootics of coccidiosis also disappear very 

 quickly. 



Infection has been shown experimentally to be due to the 

 ingestion of oocysts (cysts), either by way of the food or drink. 

 Coccidian cysts may occur on the heathei- and in the tarns and 

 pools from which the grouse drink, as before mentioned. 



When fseces of infected chicks are voided, the cpecal or soft 

 droppings are heavily loaded with cysts, and not only do they 

 foul the ground, heather, and water in their vicinity, but when 

 dried, the powdery material produced may be disseminated by the 

 wind, and so oocysts and their contained sporocysts are distributed 

 over comparatively large tracts of countr}'. 



But other methods of producing richer local infections may be 

 partly due to insects. The agency of insects such as dung-flies 

 has been observed in nature and also demonstrated experimentall3\ 



l^catophaga stercoraria, the dung-fly, commonly occurs on grouse 

 moors. The eggs of the fly are laid in fpeces and hatch out there. 

 The larvfe are large and somewhat active. They feed on the 

 fjeces of grouse, which ffeces may be infected with coccidian cysts. 

 Dissection of such larvte has shown the presence of oocysts within 

 their guts. When isolated larvfe were first well washed and then 

 allowed to defsecate on a slide, the preparation of the ffeces showed 

 oocysts when examined microscopically. Some of the prip<e also 

 contained coccidian spores in theii- guts. The fresldy hatched 

 Pkoc. Zool. Soc— 1910, Xo. XLYII. 47 



