STRUCTURE OF THE COCCIDIA. 205 



relationship. Kauffmann 1 corroborated this, and tried to prove 

 the biological independence of the cells by observing that the enclosed 

 granular masses, after being kept for a while in water, broke up 

 into four parts, and became new Psorosperm-like bodies. Arguments 

 have been constantly brought forward, down to our own day, in favour 

 of the theory that these bodies were pathologically altered cells, 2 

 and all the more so when it was established that they occurred by no 

 means exclusively in the rabbit's liver, but not unfrequently in other 

 animals and in other organs, especially in and upon the intestinal 

 epithelium. On the other hand, the Coccidia were often regarded as 

 eggs of Entozoa, such as Distomes, and particularly D. lanceolatum; 

 and, indeed, their resemblance to the latter is on superficial inspection 

 very striking, for the size and appearance of the shell are identical, 

 and the micropylar opening recalls the little lid on the Distome- 

 egg. More minute examination of fresh specimens will, however, at 

 once reveal tjie characteristic differences. 



With our present knowledge the nature of the egg-like bodies is 

 no longer a doubtful matter. The changes which they undergo after 

 they leave the body of their host, and the development which takes 

 place within the epithelial cells only admit of one explanation, that, 

 namely, which regards them as Gregarinoid parasites. 3 



Considering the importance of the intracellular occurrence of 

 Coccidium, we may perhaps note that it was Eemak who first estab- 

 lished it. The fact has been confirmed, but only for the intestinal Coc- 

 cidium, by Klebs 4 and others (Waldenburg, Eeincke, Neumann, Eimer). 

 For our knowledge of the spore-formation we are indebted to Kauff- 

 mann, who first observed it, and also especially to Stieda and Eeincke. 



Structure and Development. 



When one examines Coccidia fresh from the so-called " Psorosperm- 

 nodule," it is easy to distinguish (Fig. 106, A, B) two different forms. 



1 Loc. cit., p. 17. 



2 See among others long, Archiv f. pathol. Anat., Bd. xliv., p. 202, 1868, and Koloff, 

 ibid., Bd. xxxiii., p. 512. I must not conceal that I myself for a while supported 

 this erroneous opinion. It originated in the observation of a case in which a dog infected 

 with Trichina; showed an intestinal membrane much altered by Helminthiasis, and covered 

 throughout its whole extent with a thick layer of egg-shaped Psorospermice. See my work 

 on Trichina, first edition, p. 11, 1860. 



3 Among the investigators who have specially studied the developmental history of 

 Coccidia, Stieda alone dissents. His opinion regarding the Psorospermice, and especially 

 those inhabiting the liver of the rabbit, is that they are "very early stages of as yet 

 unknown animal parasites." I will in this connection only note that Stieda has not seen 

 the occurrence and development of Psorospermice within cells. 



4 " Psorospermien im Tnnern von thierischen Zellen," Archiv f. pathol. Anat., Bd. 

 xvi., p. 189, 1859. 



