Ophrydium Versatile. 27 



and remind one forcibly of the Stentors, only that these latter 

 are surroundedvrith. cilia, while the free Op hrydia possess anterior 

 cilia alone ; in this respect they differ from the true Vorticellce, 

 which develope a posterior fringe of cilia before the individuals 

 leave then spiral stalks. I have never seen anything like a pos- 

 terior fringe of cilia belonging to a free Ophrydium, but have 

 observed a peculiar minute setiform appendage at this ex- 

 tremity as represented in fig. C c. 



If an Ojphrydium ball be placed in a vessel of water, and be 

 kept in a sitting-room, the animalcules in a few days will leave 

 the gelatinous substance and swim freely about for a time, when 

 they again attach themselves to the bottom and sides of the vessel 

 in small radiating clusters (see fig. G), which, I believe, represents 

 an early stage of globe-like growth. I have never seen the 

 encysted state of an Ojphrydium. In most of the infusoria are 

 to be seen certain clear spaces of a circular form ; these are 

 termed " contractile vesicles," and "vacuoles." These are 

 very readily observed in Ophrydium versatile. The "contractile 

 vesicle " (fig. I d), which is supposed to be filled with some 

 clear fluid, and which some suppose may serve the purpose of a 

 rudimentary circulation, is situated in Ojphrydium near the termi- 

 nation of the oesophagus, and dilates and contracts pretty regu- 

 larly at intervals of eight or ten seconds ; the ' ' vacuoles " may 

 readily be distinguished by their non-contracting and dilating 

 properties. The " nucleus," which in Ophrydium is an elon- 

 gated twisting band, and always filled with granular contents, may 

 readily be observed by crushing an individual between two 

 pieces of glass, when the solid "nucleus" will appear. It is 

 now well known to microscopists that the so-called " nucleus " 

 and " nucleolus " of the infusoria have been most satisfactorily 

 proved to be the " ovary " and " testis," by the researches of 

 M. Balbiani. 



Refekences to Plate. — A. Ophrydium versatile attached 

 to Anacharis alsinastrum. B. Portion of surface of ditto seen 

 through lens. C. Free individual swimming by means of an- 

 terior cilia. D. Individuals in various forms. E. Granular 

 contents escaping. F. In process of longitudinal division. G. 

 Showing mode of increase. H. Filamentous alga. I. Indivi- 

 dual Ophrydium- magnified 400 diameters : — b, mouth sur- 

 rounded with cilia ; c, ciliated oesophagus ; d, contractile 

 vesicle ', e, nucleus long and twisted; /, annular folds of exter- 

 nal surface ; g, longitudinal plaits ; h 3 chlorophyll utricles ; 

 i } vacuole ; j, non- contractile peduncle. 



