1910.] Vn. U I}. FAXTUAM OS AVIAN COCCIDIOSIS. 719 



sporocysts, apparently luiharniod, were set free into the licjuid. 

 By the 5Uth day, practically all oocysts hnd either matured or 

 degenerated, and the sporocysts had begun to degenerate. 



From the above experiment, the conclusion is that the develop- 

 ment of oocysts and sporocysts is delayed by the presence of much 

 moisture, but that the power of infection is retained for a long 

 time by means o£ the sporocysts. 



Very damp air has similar efiects. 



(,8) When Ftvces are unerely kept and alloioed to dry on 

 the outside. 



When freshly voided soft droppings of grouse containing 

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

 layers rapidly develop sporocysts, the inner ones remaining 

 unatfected. 



Fa?ces kept en masse in covered dishes for as long as twelve 

 months have retained the power of infecting birds, as I have 

 lieen al)le to show experimentally. Such material contains un- 

 ditt'erentiated oocysts still, wliile its outer layers mainly contain 

 oocysts with four sporocysts within them. 



(■y) Development under Different Conditions of Temferatiire. 



For experimental purposes, it was sometimes necessary to delay 

 the development of sporocysts. This was easily done. The oocysts 

 in ffeces were transferred to a chamber kept at 1 0° C, having been 

 previously kept at 15° C. This change was sufficient to delay all 

 further development for a considei-able time. Smaller changes of 

 temperature also arrested the development of sporocysts, though 

 the eflect naturally was not so marked. 



Changes of temperatui'e and moisture on the moors may explain 

 the occurrence of occasional outbreaks of disease after all disease 

 seems to have disappeared. Moisture and coolness retard the 

 development of certain oocysts for a considerable time, dining 

 which pei'iod the disease disappears. A return of conditions 

 favourable to the Coccidium then ensues, rapid development of 

 sporocysts occui's and a fresh outbreak of disease is reported. 



YIII. Effects of Certain Reagents on Coccidian Oocysts. 



Certain experiments were made with a view to finding a means 

 of destroying oficysts without killing all other forms of life. 



This is not an easy matter. While such strong re-agents as 

 caustic potash will slowly dissolve the oocysts, their application is 

 not practicable on giouse moors. 



Salt produces plasmolysis in the end, but the process is 

 rather slow, and the salt is too readily dissolved in dew and rain, 

 and so merely soaks into the soil *. 



* However, iu this connection see Hammond Smitli, " The Field," Aug. 20, 1910, 

 Suppl. p. viii. 



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