GENUS EPISTYLIS. 703 



their parenchyma after the manner of conjugating Vorticella. At PI. XXXVIII. 

 Fig. i, Greeff's admirable illustration of a colony of this species is reproduced, 

 showing the various stages of development of the rosette-shaped clusters, and the 

 conjugation of the detached units with the normal zooids. This same authority 

 reports having observed, scattered beneath the cuticular layer of E. flavicans, minute 

 ovate capsular bodies (PI. XXXVIII. Figs. 4 and 5) that contain an extensile filament, 

 and closely corresponding in structure with the thread-cells, or nematocysts, of the 

 Ccelenterata. Such structures have not been detected in connection with this species 

 by any other observer, and the irregularity of their distribution as figured by Greeff 

 inclines the author to regard them, as in the case of Polykrikos, as of adventitious 

 origin. Two peculiarities pertain to the pedicle of the normal or erect type of this 

 species that serve to distinguish it from any other known representative of the 

 genus. In the first place, between the joints, which are solid, the structure is hollow 

 throughout, like the culm of a grass ; while secondly, these joints are tumid, and each 

 limb of the accompanying bifurcation exhibits towards its base a more or less 

 conspicuous lyrate or coarctate curvature. As with various other species of 

 Epistylis, this branching pedicle is frequently found incrusted with minute Flagellate 

 and other infusorial types. Greeff figures as growing upon examples examined by 

 him, a species evidently identical with Stein's Salpingceca convaljaria, while upon 

 the same host the author has frequently observed a species QiMonosiga and extensive 

 colonies of the minute Acinete form Podophrya carchesii. 



The soft-stemmed recumbent variety of this species, synonymous with the 

 Epistylis grandis of Ehrenberg, and which may be appropriately distinguished by the 

 title of E. flavicans var. decumbens, is perhaps better known and apparently more 

 plentifully distributed than the upright form, in consequence of the great extent of the 

 colony-masses it produces. These often constitute prominent objects to the unassisted 

 vision, taking the form of a white, granular slime, which may completely cover the roots 

 and leaves of water-plants, or spread like a grey felty mass over the side walls of the 

 tanks of an aquarium. The bodies of this recumbent variety attain a considerably larger 

 size than those found in the stiff-stemmed examples, and are usually of a brownish hue, 

 and exceedingly granular and opaque ; their substance is also more soft and plastic, 

 permitting the animalcules to assume a great variety of plicate and variously distorted 

 contours. No member of the family of the Vorticellidae probably possesses so 

 powerful and voluminous an adoral fringe of cilia as appertains to the present 

 species. It is represented by Wrzesniowski as forming four and a half convolutions 

 only ; the author, has, however, ascertained that there are no less than five and a 

 half or six turns to the spire. This was clearly demonstrated in examples isolated 

 for some time in a damp chamber ; the zooids at the end of two days became de- 

 tached from their supporting pedicles, assumed a subglobose form, and shed all 

 their cilia, presenting then the aspect shown at PI. XXXVIII. Fig. 3, in which 

 the convolution of this structure was most clearly exhibited. The detached cilia 

 remained scattered around them for a considerable interval, but ultimately disin- 

 tegrated. The under surface of dead leaves fallen into the water, as also the roots 

 and leaves of water-lilies, Nymphcea and Nuphar, are always a favourite haunt of 

 this attractive species. As evidence of its longevity it may be mentioned that 

 colony-stocks cultivated by the author in an aquarium have lasted for a period of no 

 less than six months, dating from November 1880 to June 1881, becoming metamor- 

 phosed within that period from erect tree-like colonies of two, four, or eight 

 animalcules only, to sessile masses equalling or exceeding the size of hazel-nuts. It 

 was further noted in connection with these colonies that examples isolated for 

 examination in a zoophyte-trough abandoned, within a few hours, their compact and 

 erect mode of growth for the lax and attenuate formula characteristic of the variety 

 decumbens. The brief absence of their customary food-supply was apparently quite 

 sufficient to bring about the recorded metamorphosis. 



