ISOSPORA BIGEMINA 149 



(c) Doubtful Cases. 



To these belong Virchow's case ' where, in the liver of an elderly woman, a thick 

 walled tumour measuring 9 to 1 1 mm. was found. Among the contents of this 

 tumour there were oval formations 56 /* long, surrounded by two membranes and 

 enclosing a number of round substances. Virchow considered these foreign bodies 

 to be eggs of pentastomes in various stages of development, others consider them 

 to be Coccidia. 



The Coccidia which Podwyssotzki claims to have seen in the liver of a man, not 

 only in the liver cells, but also in the nuclei, are also problematic. 2 The parasite 

 was called Caryophagus hominis. 



Again, other explanations can be given to an observation by Thomas, on the 

 occurrence of Coccidiuin oviforme in a cerebral tumour of a woman aged 40. The 

 growth was as large as a pea and surrounded by a bony substance. 3 



Genus. Isospora, Aime Schneider, 1881. 

 Syn. : Diplospora, Labbe, 1893. 



Belonging to the section Disporea, that is, forming only two spores, 

 each with four sporozoites. 



Isospora bigemina, Stiles, 1891. 



Syn.: " Cytospermium villorum intestinalium cam's et felis" Rivolta, 1874; 

 " Coccidium Rivolta" Grassi, 1882 ; Coccidium bigeminum, Stiles, 1891. 



This parasite lives in the intestinal villi of dogs, cats, and the 

 polecat (Mustela putorius, L.). According to Stiles, 4 the oocyst 

 divides into two equal ellipsoidal portions or sporoblasts which 

 become spores and then each forms four sporozoites. The oocysts 

 of this species vary from 22 //, to 40 //, in length and from 19 /JL to 

 28 //, in breadth. Each spore is io//, to 18/1, long and contains 

 four sporozoites. The parasites live and multiply, not only in the 

 gut epithelium, but also in the connective tissue of the intestinal 

 submucosa. Wasielewski has seen merozoites in the gut of the cat. 



Isospora bigemina (fig. 75) appears to occur also in man, for 

 Virchow published a case which was communicated to him by 

 Kjellberg, and attributed the illness to this parasite. 5 Possibly also it 

 would be more correct to ascribe the observation of Railliet and 

 Lucet, which is mentioned under " Human Intestinal Coccidiosis," 

 p. 148, to this species, as the Coccidia in that case were distinguished 



1 Arch. f. path. An., xviii, 1860, p. 523. 



2 Podwyssotzki, " Ueb. d. Bedeut. d. Coccid. in d. Path. Leber des Menschen," CentralbL 

 f. Bakt., vi, 1889, p. 41. 



3 Thomas, J., "Case of Bone Formation in the Human Brain, due to the Presence of 

 Coccidium oviforme" Journal Boston Soc. Med. Sc., iii, 1899, p. 167 ; Centralbl. f. Bakt. 

 [ij xxviii, 1900, p. 882. 



4 "Notes on Paras.," No. n, fourn. of Comp. Med. and Vet. Set., 1892, xiii, p. 517. 



5 Arch. f. path. An., 1860, xviii, p. 527. 



