ANIMAL PARASITES AND DISEASES. 51 



The feathering- also is very weak compared with that of healthy birds ; 

 that of the legs is ragged, the quills are less rigid, the sheen on the 

 feathers is less developed, and the replacement of nestling down by 

 ordinary feathers is much retarded in diseased birds. 



Owing to the attack of the parasite on the mucous membrane of 

 the alimentary canal digestive troubles occur, and the faeces voided 

 by the grouse are the best ordinary index of its condition. The soft 

 droppings of such grouse (which are caecal in origin) are very fluid, 

 the condition being one of diarrhoea. The dejecta are very pale, 

 softer than usual, and of a sulphur yellow colour, those of normal 

 grouse being olive green to brown in hue. Examined microscopically, 

 a small portion of infected faeces, diluted with water, shows myriads 

 of small oval bodies, which are the resistant forms of the parasite, 

 known as oocysts (or cysts) forms by which the infection of new hosts 

 is readily brought about. Death from coccidiosis is often sudden, and, 

 a point of great importance, corpses of all diseased birds should be 

 burned and never buried, for, as I have proved experimentally, the 

 cysts remain infective for long periods, even for a year or more 

 long after the disintegration of the body of the first host." 



DISSEMINATION OF THE DISEASE. 



The disease spreads with remarkable rapidity. The faeces are 

 the chief source of contamination, and as these dry they are distri- 

 buted by the wind in the form of dust, which contains the parasites in 

 various stages of development. 



The parasites are taken into the body of the fowl by the fouling 

 of food and drinking w r ater. 



Dr. Fantham (loc. cit.) has shown that rain is an important factor 

 in dispersing the dejecta of infected birds, and also that a small 

 dipterous fly, Scatophaga stercoraria, Linn., lays its eggs in the 

 droppings of infected birds, the larva developing there. Such larvae 

 and flies, when examined by him, were found to contain in their 

 intestines and dejecta the oocysts of the parasite. 



PREVENTIVE AND REMEDIAL MEASURES. 



All dead bodies and infected droppings should be burned ; indeed, 

 where an outbreak occurs, and there are only a small number of birds 

 concerned, it is by far the wisest plan to destroy the lot. 



