ON DRKPANIDIUM RANARUM. 57 



It was inferred from Lieberkiihn's descriptions and figures of 

 Gregarines velues (noticed also by Stem), tiiat some, at least, of 

 the forms of Gregarina to be met with m the testicular sac of 

 the Earthworm, which were enveloped in a vesicle carrying 

 conical processes on its surface, were in fact sperm polyplasts 

 which had been penetrated in an early condition of their develop- 

 ment by young Gregarinee.^ The Gregarina had grown and 

 more or less tightly fitted to its cell host, which also had 

 proceeded on its development and produced in a somewhat 

 abnormal form its crop of spermatoblasts. 



1 do not mean to say that all the varieties of Gregarinse with 

 peculiar cuticle-like investments, which are to be observed in 

 the Earthworm are to be explained as the result of the parasitism, 

 of the Gregarina in a sperm-cell. But such forms as those 

 figured by Lieberkiihn in the plate i, fig. 7, of his ' Evolution 

 des Gregarines^ (published as a memoire couronne (1854) by 

 the Belgian Academy), and such as figured in my Plate YII, 

 figs. 26, 28 of this Journal, 186'3, illustrating a notice of " Our 

 present knowledge of the Gregarinse," certainly are instances of 

 this mode of parasitism. More recently, Butschli (' Zeitsch. 

 wiss. Zool.,' vol. XXXV, 1881) has shown that sometimes (jrregaringe 

 parasitic in the Earthworm penetrate the epithelial cells of the 

 ciliated funnels of the spermatic duct, and such a Gregarhia may 

 remain implanted by one end in the cell after attaining fifty times 

 tlie linear dimensions of the cell in which it was once parasitic. 



The cell-parasitism of the Sporozoa at a certain stage of their 

 existence has been chiefly demonstrated through Eimer^s obser- 

 vations on the oviform psorosperms (for which Leuckart adopts 

 the generic name Coccidium) of the House-mouse, and through 

 Aimee Schneider^s discovery of the falciform corpuscles which 

 form within the pseudonaviculse oi31onocystis lumbrici (see fig. 5 c) 

 and other Gregarinse, and serve by their presence to efl'ectually 

 estabhsh the relationship of the several phases in the life-history 

 of Eimer's Coccidium with the several phases in the life-history 

 of typical Gregarinse. 



Eimer found spherical Gregarinse (Coccidium) existing as 

 cell-parasites in the epithelial cells of the intestine of the House- 

 mouse.^ This minute Gregarina, without great increase of size, 

 envelopes itself in a transparent cyst, and breaks up internally 



• See especially Lieberkiibn, ia ' Reichert and Du Bois Redmond's 

 Arcliiv,' 1865. 



- Lieberkiibn also describes and figures the Coccidium oviforme of the 

 rabbit as a cell-parasite in the intestinal epithelium in bis 'Evolution des 

 Gregarines/ already cited, 1S54. A valuable and detailed history of our 

 knowledge of the Sporozoa, especially of Coccidia, is given by Leuckart 

 in llie new edition of his ' Parasiten des Menchen,' part i, p. 241, 1879. 



