COCCIDIA 73 



In the liver of the rabbit, the Coccides inhabit the gall-ducts, 

 where they cause cystic enlargement, the swellings being visible to 

 the naked eye as largish yellow knots. In the acute condition which, 

 when infection is severe, may end fatally, these knots are taut and 

 elastic to the touch. They are filled with a thin pus-like liquid which 

 should be examined under the microscope, either fresh or as a smear 

 preparation by the method given for the Coccidia of Lithobius. This 

 liquid will be found to contain numerous parasites in various stages 

 of schizogony. When the disease has passed its height, the cyst- 

 contents become drier and more like crumbling cheese. 



The asexual forms are very numerous in the knots with liquid 

 contents ; in those with drier contents only encysted parasites are, 

 as a rule, found. 



In the living state, the developing schizonts are easily distinguished 

 from the epithelial cells which harbour them by their greater refrac- 

 tivity. The multiplication of the nucleus, which precedes the multi- 

 plication of the cell, frequently commences before the end of the 

 period of growth. The resulting merozoites are more numerous than 

 in the Coccidia of Lithobius and the details of schizogony are con- 

 sequently more difficult of observation. The number of microgametes 

 formed from each microgametocyte is also greater and the size of 

 the individuals (which are actively motile) is consequently less. 



The macrogametocytes are easily recognized by the numerous 

 granulations in the superficial layer of plasma, which, under certain 

 conditions, may resemble small nuclei, similar to those which appear 

 in the microgametocyte during the formation of the microgametes. 

 The presence, however, of a large undivided nucleus in the interior 

 of the macrogametocyte will prevent any confusion of the forms. In 

 older growths, next to the encysted parasites, the macrogametocytes 

 are the forms most frequently encountered. 



The immature macrogametocytes are ball-shaped, while the 

 fertilized macrogametes assume an oval form. The oocysts, which 

 are formed by the secretion on the part of the macrogamete of a 

 doubly contoured envelope, are also oval in form. The next stages 

 take place, not within the liver or intestine of the rabbit, but in the 

 open air, oxygen being necessary to their further development. To 

 follow these stages under the microscope, faeces or gall containing 

 oocysts should be spread out in the air. Material taken from growths 

 in the liver does not yield reliable results, as oocysts which are 

 retained for any length of time in the liver, become injured to such an 

 extent by the large amount of carbonic acid which it contains, that 

 they lose their power of development and become degenerated. In 

 the gall-bladder of rabbits suffering from coccidiosis of the liver, a fine 



