waldenbueCt's observations. 215 



all that we know of the reproductive processes of related organisms. 

 This blank has, however, been filled up by other experiments con- 

 ducted by Waldenburgi and Eivolta,^ who, by feeding with Coccidia 

 containing Psorospermice, produced new Coccidia. Eivolta expressly 

 remarks that the presence of the Psorospermice is an essential con- 

 dition of success, since Coccidia with unsegmented contents remained 

 without change in the alimentary canal of the animal experimented 

 upon. Since Eivolta experimented on fowls, and since the Coccidia of 

 these animals represent a distinct species, let us restrict ourselves first 

 to an experiment of Waldenburg's, made on a rabbit four weeks old, 

 and of healthy stock. 



Use was made of intestinal Coccidia ^ with their contents divided 

 into four, and still in their original place of formation — that is, in the 

 harbouring organs. On the fourth day after feeding there were found 

 on the surface of the intestinal mucous membrane not only a few 

 small mature "Psorospermice" {i.e., Coccidia), but also "numerous round 

 distinctly nucleated bodies, with a fine, often indistinct, membrane, 

 and granular contents lying closely upon it," — bodies in fact perfectly 

 resembling the young Coccidia, usually found enclosed in the epi- 

 thelial cells. Control observations made on other rabbits born and 

 bred with the one experimented on gave a negative result. As to 

 finding the parasites free on the mucous membrane of the infected 

 animal, Waldenburg concludes that immigration " into the epithelial 

 cells is by no means necessary for the development of the Psoro- 

 spermice, especially since in other cases one only finds a comparatively 

 small number shut up in the cells." 



Against this statement a subsequent conclusion of Waldenburg's 

 must be placed, although he still upholds the cogency of his feeding 

 experiment. By cultivation of liveT-Coccidia, he was convinced that 

 the series of changes undergone by the parasite in its free life is by 

 no means terminated by the formation of the spores above described. 

 He denies that the four enclosed bodies are Psorospermice. They are 

 considered as segmentation-spheres, which, beside and in addition to 

 the granular mass, enclose a clear nucleus at the poles. He contends 

 against calling these nuclei the ends of a distinct rod-like body, and 

 would indeed dispute the existence of any such thing. 



After some time the number of these nuclei doubles. Within the 

 membrane of the Coccidium there then appear segmentation-spheres, 



' Loc. cit., Bd. xxiv., p. 163. 



- " Parass. veget.," p. 390. 



' A careful examination of these fragments was not undertaken by Waldenburg, who 

 at that time was only acquainted with the investigations of Kauffinann. According to tho 

 figures, they are normally developed Psorosperms. 



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