ZOOLOGICAL AND BOTANICAL ASSOCIATION. 125 



can be expelled by fracturing the cell by pressure. This central portion 

 is extruded in a cohering, somewhat stringy mass, but can be afterwards 

 broken into granules. It is sometimes shot out with vigour, leaving the 

 separate chlorophyll-granules behind, and which afterwards, in a conti- 

 nuous stream, make their exit through the ruptured cell- wall. The ex- 

 pelled chlorophyll granules, which at first are large and smoothly denned, 

 by subsequent pressure can be broken up into smaller granules, which, 

 when detached, as in other cases, often set up a " molecular" motion in 

 the surrounding water. I have noticed, too (rarely), a molecular motion 

 of the more minute particles within the uninjured cell. 



This organism has occurred not unfrequently in the Desmidian ga- 

 therings I have made ; but nowhere did I meet with the plant in such 

 numbers, and so isolated from other forms, as in a small pool, close to the 

 Sugarloaf Mountain, on the road to Roundwood. I have specimens 

 still by me collected during last summer, and which, living ever since, 

 have been healthfully preserved. A single specimen is visible to the naked 

 eye, being from -rfc to ^hs of an inch in diameter. The chief difficulty ad- 

 verted to in reconciling this with M. Hofmeister's plant is the comparative 

 dimensions, as he says with regard to this — " Some are as much as *05 

 millim. in diameter." This is (roughly) about equal to shs of an inch, 

 the dimensions of my specimens being thus often three times as great. 

 "When I first met with individual specimens of this organism, I imagined 

 it might have been the sporangium of some Desmidian (possibly of a 

 Tetmemorus), though, as I afterwards found, too large for that. M. Hof- 

 meister compares his plant to the sporangium of Xanthidium armatum, 

 as if similar in size, and which it no doubt resembles. But though 

 Mr. Ralfs met with but one specimen of the sporangium of that (with 

 us) rather common species, and does not give the dimensions, yet it is 

 surely not much smaller, according to his figure (comparing it with 

 others of known size, and all equally magnified), than *foj of an inch. 

 However, the conjecture that our plant can be sporangium seems to bo 

 dispelled by its undergoing self-division ; and, as Hofmeister remarks 

 with "regard to his plant, " this renders it in the highest degree probable 

 that they are independent organisms, — Desmidiaj without a central con- 

 striction, which may form the commencement of a series of forms termi- 

 nating in Micrasterias." 



M. Hofmeister does not describe the mode of division in his plant. 

 That met with here, when about to divide, appears to be more densely 



