"GROUSE DISEASE " COCCIDIOSIS 259 



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



Much moisture is present on many moors, and droppings 

 of infected chicks contain coccidian spores which not only get 

 washed into the soil, but also into the pools, springs, and tarns, 

 at which Grouse drink. It is, therefore, of some importance 

 to determine the time required for the death of the resistant 

 spores of the parasite in water. 



Coccidian oocysts were placed in water, kept at about 20 

 degrees C., the water being replaced as required, to avoid 

 evaporation effects. Ordinarily, the oocysts develop sporocysts 

 or spores very rapidly in two to three days. In the case of 

 cysts kept in water, nine days elapsed before much change was 

 noted. At the end of that period, a few oocysts showed some 

 development, and still fewer showed four sporocysts. Two 

 days later many more oocysts contained four sporocysts, and 

 this progressive development continued for some days. Few 

 signs of decay were seen until about the fortieth day, when 

 some showed signs of gas bubbles in their interiors. Others, 

 however, had completed their development, and their four 

 sporocysts, apparently unharmed, were set free into the 

 liquid. By the fiftieth day practically all the oocysts had either 

 matured or decayed, and the sporocysts had begun to die. 



From the above experiment, the conclusion is that the 

 development of oocysts and sporocysts is delayed by the presence 

 of much moisture, but that the power of infection is retained for 

 a long time. 



Very damp air has similar effects. 



These observations are borne out by observations in the 

 field ; a moist spring is seldom associated with ^erious loss of 

 young birds unless the rainfall is sufficiently heavy to cause ex- 

 tensive drowning. 



(b) When Fceces are merely kept and allowed to dry on the outside. 



When freshly voided soft droppings of Grouse containing 

 coccidian oocysts are allowed to dry, the oocysts in the surface 



