CHAPTER LVII. 

 THE COCCIDIIDEA. 



Section I. The genus Coccidium, p. 760. 



1. Coccidium cuniculi, p. 760. 



Morphology, p. 761. Life history, p. 762. 



2. Other principal species of Coccidia, p. 764. 

 Section II. The genus Klossia, p. 765. 



Section III. Parasites in tumours, p. 766. 



1. Coccidia, p. 766. 2. Micrococcus neoformans, p. 769. 



[THE Coccidiidea are Sporozoa belonging to the sub-division Telosporidia 

 parasites " in which the reproductive phase of the life-cycle is distinct from, 

 and follows after, the trophic phase " (Minchin).] 



The Coccidia are found as intra-cellular parasites both in the Vertebrata 

 and in the Invertebrata. 3 



The Coccidia are small, oval or spherical, nucleated amoeboid bodies with 

 granular protoplasm. Reproduction takes place both asexually (schizogony) 

 and sexually (sporogony). The investigations of Leger and of Mesnil have 

 shewn that the Coccidia should be classified with the Haematozoa 

 (Chap. LVIIL). 



SECTION I. THE GENUS COCCIDIUM. 



Coccidium cuniculi. 



(Coccidium oviforme.} 



Whitish or yellowish masses resembling small softened abscesses and con- 

 taining oval-shaped structures similar to the eggs of Nematodes are frequently 

 to be found lodged in the hepatic canaliculi or parenchyma of the livers of 

 rabbits: these masses are in reality Coccidia. A Coccidium consists of a 

 retractile enveloping membrane, granular protoplasm, nucleus and nucleolus. 



The infection in the rabbit often resolves spontaneously : the Coccidia are expelled 

 as oocysts (vide infra), and on post mortem examination nothing more than cicatricial 

 scars on the surface or in the substance of the liver are left as an indication of a 

 previous infection. In young rabbits Coccidia may multiply very rapidly (Pfeiffer), 

 in which case the infection is scattered throughout the liver ; the biliary canals are 

 dilated and the connective tissue hypertrophied, compressing the blood-vessels 



1 Speaking generally, the evolution of the Coccidia takes place within the cells of the 

 animal infected. Laveran and Mesnil have, however, described a Coccidium in a tortoise 

 in which the development was entirely extra-cellular : this may perhaps also be the case 

 with C. bigeminum (vide infra). 



