20 NATURAL HISTOKY SOCIETY OF DUBLIN. 



to the cell- wall at each end (Pigs. 2 to 6). In the middle of the chloro- 

 phyll-plate there is usually a starch grannie within the central projec- 

 tion or swelling-out. If a cell seen from the point of view showing 

 thus the edge or lateral view of the chlorophyll-plate he caused to make 

 a quarter of a revolution on its longitudinal axis, the chlorophyll- plate 

 presents its hroad or front surface to the ohserver, provided it be not 

 obscured by the too dense remaining contents, when it is seen to be 

 (of course less intensely, but) uniformly green. De Bary describes for 

 If. Braunii this chlorophyll-plate to be minutely toothed at the margin; 

 but, so far as I can see, if I be right in my identification of the plant, 

 it would, perhaps, be more correctly described as irregularly crenate. 

 Exceptionally and rarely the chlorophyll- plate possesses three (or four, 

 De Bary) planes, presenting in end view a triradiate (or quadriradiate) 

 figure. The remainder of the cavity of the cell may be apparently 

 entirely filled by a rather coarsely granular peculiarly coloured endo- 

 chrome, or it may be destitute of it, or nearly so, possessing then, 

 besides, only watery or colourless contents. In the latter case, indeed, 

 is the chlorophyll-plate best seen ; and then only, or when the granular 

 endochrome is but sparing, can it be discerned at all in front view. 

 But in certain species an intermediate condition appears to be the most 

 common ; that is to say, the whole of the remaining cavity of the cell 

 is not filled by the granular endochrome, but the latter forms only a 

 parietal layer, sometimes somewhat sharply defined within, and leaving 

 a clear intermediate space between it and each broad or front surface of 

 the chlorophyll-plate. In If. violascens (De Bary) about the middle of 

 the parietal layer, at one side, there may be often seen a little depres- 

 sion. This sometimes contains a little corpuscle or granule ; but I have 

 by no means always, or indeed often, been able to detect it. De Bary 

 considers this a nucleus. In If. Braunii, and his If. chlamydosporum, 

 this nuclear body seems to be in contact with the plate. In this genus, 

 when a cell has attained the full length proper to the species, self-divi- 

 sion sets in. As in all the elongate forms, here also the line of division 

 takes place transversely, cutting the cell into two in a line at right angles 

 to its longitudinal axis. A division of the chlorophyll-plate either 

 precedes it, or is apparently affected by it, according to the species. 

 In young daughter -cells, immediately after division, when the central 

 corpuscle is to be seen, it occupies in each a place near the septum ; by 

 and by, each is again found at the middle of its chlorophyll-plate both 

 as regards the longitudinal and transverse diameters. Beproduction in 

 this genus, as in Cylindrocystis, is by conjugation and evolution from 

 the spore-cell, in germination of four young cells identical with the 

 parent.* In this genus, however, the foregoing characters are in some 

 species often not easy of application, owing to the density of the granular 

 cell-contents obscuring a proper view of the internal structure, and to 

 the specimens not being in a conjugated state. 



* De Bary, op. tit,, p. 34, t. vii,, 20-?9. 



