COCCIDIIDA 71 



above all, to demonstrate the correctness of this view as regards other 

 species of coccidia also, and for this purpose he utilised the experiences 

 already published. Coccidia were known to exist in a number of different 

 hosts, and to propagate in some according to the Coccidium type, in others 

 according to the Eimeria type ; it therefore stands to reason that in this 

 case it was not the question of two species belonging to different genera 

 living side by side, with a different manner of development, but of one 

 species, in the life of which both manners of development occur alternately, 



This interpretation of facts was combated especially by A. Schneider (16) 

 and by Labbe (17), but has, nevertheless, proved true, apart from the 

 circumstance that Schuberg(iS) succeeded in discovering the hitherto unknown 

 Coccidium form in the intestine of the mouse ; and that, moreover, Leger con- 

 firmed the fact that there are no arthropoda in which Eimeria are not found 

 together with coccidia. The question was finally settled by experiments made 

 by Leger (19) with the coccidia of Scolopendra cingulata, by Schaudinn and Sied- 

 lecki (20) with those of Lithobius forcipatus, and by Simond (21) with the coccidia 

 of the rabbit. On Simond's suggestion the sickle-shaped germs correspond- 

 ing to the sporozoites, which are formed by endogenous sporulation, are 

 universally termed MEROZOITS ; and in accordance with Schaudinn's suggestion, 

 those individuals which form merozoites are termed SCHIZONTS, and those 

 which produce shelled spores are called SPORONTS. In contradistinction to 

 sporogony (exogenous sporulation), one therefore speaks of schizogony 

 (endogenous sporulation). 



The more minute examination of these processes at last led to the 

 discovery of SEXUAL DIMORPHISM, of copulation and alternation of genera- 

 tion in the coccidia. Schuberg was the first to consider the possibility of 

 copulation in coccidia ; in addition to the formations which now are 

 termed merozoites, he observed very diminutive bodies (" microsporozoites ") 

 in the coccidia of the intestine of the mouse, which were able eventually 

 to perform copulation. Labbe confirmed this observation in some of the 

 species, and Simond (21) expressed the opinion that "chromatozoites" 

 occurred in all coccidia. Copulation itself was then observed by Schaudinn 

 and Siedlecki. The copulating bodies are termed gametes : as, however, 

 they differ considerably one from the other, the males are called micro- 

 gametes (i.e., the microsporozoites of Labbe and the chromatozoites of 

 Simond) and the females macrogametes. After copulation is completed 

 sporogony takes place, and in the cycle of development of one species this 

 regularly alternates with schizogony (asexual propagation). 



The recognition of this unsuspected complicated process was bound to 

 effect reforms in the classification of the coccidia ; and all the forms that 

 had been regarded as developmental stages (Eimeria, &c.) had to be 

 eliminated from the system. 



LITERATURE. 



(1) HAKE. A Treat, on Varic. Capill. as constit. the Structure of Carcinom. of the Hep. 



Ducts, with an Account of a New Form of the Pus Globule. London, 1839. 



(2) NASSE, H. Ueb. d. eiforrn. Zellen d. tuberkelahnlichen Ablagerungen in d. Galleng. 



d. Kaninchen (Arch. f. An. u. Phys., 1843, P- 209)' 



(3) REMAK, H. Diagn. u. pathogen. Unters. Berlin, 1845. 



(4) LIEBERKUHN, N. Ueb. d. Psorospermien (Arch. f. An. u. Phys., 1854, p. i). 



Evol. des Greg. (Mem. cour et Mem: d sav. etrang. Ac. d. Belg., 1855, xxvi. 



