THE ANIMAL PARASITES OF MAN 



and sporulate in the open within a fortnight or three weeks. 

 The fully-developed spores are of a broad fusiform shape and 

 measure 0-012 0-015 m *n. in length, with a breadth of 0-007 

 mm. They contain two sporozoites, broad at one end, pointed 

 at the other, which lie in such a position that they form a bent 

 dumb-bell-shaped body (fig. 32). A granulated residual body lies 

 in the concavity. In sporulation the whole of the plasm of the 

 sporont is taken up, and therefore in the oocyst there is no 

 residual bodv. 



F IG . 3!. Coccidium cuniculi (Riv.), from the liver of the rabbit, sporulating 

 (a) Entirely occupying the integument (oocyst) ; (&) gathered together in a nucleated 

 ball ; (c) divided into four spores. 



>?- FIG. 32. -Spores of the Coccidium cuniculi (Riv.), with two sporozoites and resi- 

 dual bodv a free sporozoite to^the right (after Balbiani). 



The development of this species does not deviate from the 

 course sketched above. Infection occurs through swallowing spores 

 or oocysts containing spores. 1 The gastric juice, as already stated 

 by Rieck, causes the spores to open and the sporozoites to become 

 free ; the latter then utilise the ductus choledochus to reach the 

 biliary ducts, where they penetrate the epithelial cells and propagate 

 by means of schizogony. 2 



According to the number of spores taken up there ensues, 

 sooner or later, at those parts of the biliary ducts that are 

 attached, inflammation with proliferation of the epithelium and con- 

 nective tissue of the passages, which become greatly thickened at 

 the expense of the substance of the liver. 3 Finally, irregular 



1 Pianese's statement (Arch. d. parasit., 1899, u -> P- 397) that the ingestion of oocysts 

 before they have sporulated causes infection still lacks confirmation. It cannot, 

 indeed, be denied that the animals experimented on finally became infected, but the 

 necessary assumption that the oocysts developed further in the intestine is highly 

 improbable. I consider it much more probable that the oocysts ingested were passed 

 through the intestine, sporulated outside, and were then again .taken up by the 

 animals experimented on. 



2 Podwyssotzki, W., " Z. Entw. d. Cocc. ovif. ah Zellschmar otter " (Bibl. med. Cassel, 

 1895, part D., ii., No. 4) ; Pianese, G., " Le fasi di svil. del Cocc. ovif." (Arch, de paras., 

 1899, ii., p. 397). 



3 Felsenthal and Stamm, " Verdnd. in Leber u Darm. b. d. Coccidienkrankh. d, 

 Kaninch." (Vtrchow's Arch. f. path. Anat., 1893, cxxxii., p. 36). 



