11)10. I DU. II. li. l'ANTll.\.M ()\ .VVI.W COCCI DKiSIS. 7()9 



grouseanil responsible For tlie (hvindling of the broods, itiirticiiliirlv 

 ill the spring and early summer, was found to be equally injurious 

 to healthy young fowls and young pigeons. Healthy grouse chicks 

 also were experimentally treated by administering food mixed 

 with small quantities of infected fceces from other gi-ouse suffering 

 from coccidiosis, and fatal results ensued. 



The results set forth in this memoir are those ol)tained from 

 one season's work only, to which my investigations w^ere limited. 



II. EXPERIMKXTAL MetJIOUS. 



The birds used in experimental coccidiosis were grouse chicks, 

 fowl chicks and young pigeons, all of which wei^e initially liealthy. 

 Coccidian oocysts (PI. LXII. ligs 4, 5) contained in ctecal droppings 

 from infected grouse were allowed to develop spores to some 

 extent hj being thinly spread in Petri dishes and covered in order 

 to prevent complete drying. Under these conditions the spoi-es 

 (ligs. 6, 7) developed in two to three days at summer tempera- 

 ture. The fajces so prepared wei-e then administered to the 

 healthy young birds. 



(A) Grouse Chicks. — As these birds are somewhat wild, even 

 though bred in captivity, a rapid feeding method was ado])ted. 

 Some of the partly dried ftecal matter was taken up on a spatula 

 and inserted directly into the month of the bird. llather large 

 (juantities Avei'e given as first doses, but if infection was not fairly 

 rapidly brought about the dose was i-epeated. The c;ccal droppings 

 of treated chicks were collected each moi-ning, for these soft 

 di'Oppiiigs are more abnndant during the night than they are 

 during the day, and in the early morning there is a better chance 

 of obtaining excrement free from soil. Examination of fieces 

 collected in the evening was sometimes made. 



The grouse chicks were kept on the experimental ground at 

 Frimley, and the feeding experiments were conducted by Dr. E. A. 

 Wilson, to whom I tender my best thanks. Sanqiles of the faeces 

 of the birds were sent to me daily. 



(B) Fowl Chicks and Youiuj Pigeons. — A meth(i(l of feeding 

 similar to that used for grouse chicks was employed witli fowl 

 chicks and young pigeons (s(jual)s). These experiments were con- 

 ducted by me at Ca-mbridge. The chicks used were from incubated 

 eggs, the eggs having been carefully cleansed antiseptically before 

 incubation. C;ecal di'oppings containing oocysts were administered 

 directly to the birds. Very small daily doses were used for several 

 days and then none for a couple of days, and so on. This method 

 of administering oocysts was quite effective and had the advantage 

 of reproducing somewhat the condition of wild grouse on the 

 moors, where intermittent ingestion of oocysts with food or drink 



OCCUl'S. 



One experiment Avas performed in which a .single dose only had 

 a fatal effect on a fowl chick. 



])rr>ppings containing oocysts in difTorent stages of ilcvclopmont 



