126 DUBLIN UNIVEBSITY 



filled with endochrome than in the ordinary condition, and its somewhat 

 radiate appearance is less evident : — the first indication of the approach- 

 ing occurrence of the process of division is the separation of the endo- 

 chrome, which becomes, as it were, cut through-and-through abruptly 

 into two exactly hemispherical masses, separated by a straight, sharp, 

 smooth line ; a slight elongation of the cell next occurs, which goes on, 

 pari passu, with a constriction of the cell-wall immediately over the 

 equatorial line of separation of the endochrome, at which stage the divid- 

 ing cell becomes of a figure of 8 form. The first I met with undergoing 

 this process I thought might be in a state of partial conjugation ; but by 

 a little further observation it became evident that this was a process of 

 division. When a specimen has become so far divided, it has assumed 

 a quasi-Desmidian appearance, as it might possibly be taken for a large 

 Cosmarium ; but the separated halves of the endochrome of the original 

 spherical cell soon lose their exactly hemispherical form, grow larger, 

 and become rounded off, having secreted a special cell-membrane, and 

 eventually, as two distinct individual cells, similar to the parent, emerge 

 from its loose old cell- wall by rupturing it (Fig. 17). This escape of 

 the newly formed spheres seems to occur sometimes before the constric- 

 tion of the old cell becomes entirely cut off. At other times this con- 

 striction is perfected, and single cells are thus frequently met with, the 

 old cell- wall surrounding the newly formed cell like a loose tunic. 



Supposing that M. Hofmeister's plant follows the mode described, 

 might not the bursting (at the annular groove) of the constricted old 

 cell, before the deepening constriction becomes entirely cut off, account, 

 at least in some measure, for the openings or orifices described by him as 

 met with in the empty coat ? I have myself in our plant often found the 

 cast-off coats, which are met with usually collapsed or wrinkled, and 

 sometimes with an orifice like what might be supposed to occur under the 

 conditions indicated. However, M. Hofmeister relates his having occa- 

 sionally noticed as many as six coats inside each other. In the plant met 

 with by me I have not seen more than one inside another. I am not able 

 to state that in our plant the cell-contents, without division, first con- 

 tracting, secrete a new cell-membrane still within the original coat, — 

 such a process being, I imagine, the onty way to account for the fact of 

 several loose coats concentrically surrounding the same cell. Thus, 

 while it appears as by no means decided that M. Hofmeister's plant and 

 that alluded to as met with here, are identical, yet I think it will be at 



