32 NATURAL HISTORY SOCIETY OP DUBLIN. 



be by the breaking up of the original cells, for no special opening seems 

 to occur, if indeed those alluded to be not possibly really internal pa- 

 rasitic growths. Therefore, so far as I know, the only apparent parallel 

 for the curious phenomenon in this plant is the probably similar bodies 

 which occur in Zygnema just alluded to. But they are possibly struc- 

 tures of an analogous nature. 



I do not at all suppose that the apertures here left by the raising off 

 of the lid-like portions of the cell- wall are by any means to be regarded 

 as for the purpose of admission of spermatozoids — that is, these spore- 

 like bodies have no resemblance to the germ-cell (oospore or BefrucM- 

 ungskugel, Pringsheim) of CEdogonium. Nothing of the sort was appa- 

 rent, nor is it to be looked for or expected. The true generative act, as 

 I regard it, is found in these species in that of Conjugation. 



Measurements. — Length of cell, j^ to h ^q ; breadth, T ^ g to y^Vo > 

 diameter of spore-like body averages about T q o"o °^ an i ncn - 



Plate I., Fig. 20, cell showing edge view of chlorophyll-plate. 

 Pigs. 21-22-23, cell-contents emerging. Pigs. 24-25, cell-contents 

 emerged, and balled together into a spore-like body, of a reddish colour. 

 Pigs. 26 to 31, various empty cell-membranes, showing the valve or 

 lid-like portion detached. 



Affinities and Differences. — This is the only species I am acquainted 

 with which reaches the size of M. Braunii, but it differs from that in 

 the pale colour of the mass, in the broadly elliptic, not cylindrical cells, 

 in the much narrower chlorophyll-plate in edge view, in this not being 

 proportionately so much expanded at the ends or at the middle, in 

 its not reaching the extremities of the cells, and in its being more fre- 

 quently eccentric and somewhat curved. It more resembles M. violascens 

 in figure ; but it is of larger size and different colour, the chlorophyll 

 plate in edge view is narrower and more pointed, the cells are not so 

 broadly rounded at the ends, the endochrome is less dense but more 

 scattered, and the parietal layer not so well marked. It is distinguished 

 from M. chlamydosporum by its elliptic, not cylindrical outline, by its 

 greater width in proportion to its length, by its not shedding its coat 

 during division. Its elliptic, not cylindrical, figure, and densely gelati- 

 nous habit separate it from M. Endlicherianurn (Nag.). I do not set any 

 distinctive value on the remarkable phenomenon of the extrusion of the 

 cell-contents through a valvular opening, as I conceive, whatever it 

 portend, there may be nothing to prevent a similar occurrence in any 

 other species. 



While I have to apologize for the discursive tendency and rather 

 irregular arrangement of this paper, I am, at the same time, indeed, well 

 aware that there is far more in it that is not new than that is so, and 

 that the former has already been much better laid down by De Bary 

 than I could ever hope or pretend to do ; but the former was necessary 

 to illustrate and elucidate the latter, and I know of no English work in 

 which, as I imagine, these plants are properly described. Therefore I 

 consider that the little that is new in these remarks will not be with- 

 out its value as a contribution, small though it be, towards an eventually 



