236 DESCRIPTION OF [Polycfastrica. 



vegetables, and adduces no other reason for his deijial of the vege- 

 table nature of some genera; but the bisection of cells is very 

 frequent, if not universal, in the more simple Algse ; and Mr. Ralfs 

 is of opinion that the process is identical mth that witnessed in the 

 Desmidiece. 



'* I (says Mr. Ralfs) am not in a position either to deny, or to affirm, 

 ■with confidence, the presence of openings in the extremities of the 

 Closteria. It appears to mc, indeed, that in Closterium, there is a 

 slight notch, or more usually the rudiment of one, at the apex of the 

 s( gments, — a mere indication in short of what is fully developed in 

 Tetmemorm and Euastrum. In no instance, can any portion of the 

 contents of the cell be forced out from the extremities. On this 

 subject, the views of Ehrenberg, and Mr. Dalrymple, are given at 

 page 180. Mr. Ralfs has the following remarks upon them. 



"I confess I am unable to refer to any example in other Algse of 

 terminal globules, like those present in the Closteria, but neither can 

 one be foimd amongst animals ; and if in some respects they have an 

 analogy with organs belonging to the latter, in others they agree 

 better with vegetable life. The contained granules seem to me to 

 differ in no respect, except in position and uninterrupted motion, 

 from other granules in the same frond, and, as I have already stated, 

 I once saw the motion continue after their escape from the cell, pre- 

 cisely as ill other zoospores. Meyen observes that the functions of 

 these bodies are very difficult to detenniue, but they are to be foimd 

 in very many Confervse, and are perhaps to be likened to the sper- 

 matic animalcules of plants. 



"The contraction of the internal membrane of the Closteria, or the 

 expulsion of their contents on the appKcation of iodine or other 

 re-agents, cannot be relied upon as a satisfactory test for determining 

 their nature, for the blandest fluids will, in some cases, occasion 

 violent action. From the experiments of Mr. P. Grant, it seems 

 that the re-action of a re-agent cannot be predicated with any cer- 

 tainty, and that the molecular action is not affected by several strong 

 poisons, whilst it yields to other substances less generally dele- 

 terious. 



"With regard to the " supposed ova," I fully agree with Meyen, 

 that tliey are similar to the green corpuscles found in the cells of 



