ON PLASMOLYSIS. 165 



phenomenon described is universal, it must at least be ad- 

 mitted that it is very general. I may here suggest that some 

 difference may be found between the relation of the proto- 

 plasm to the cell wall in young and in old cells ; no such dif- 

 ference has been uniformly observed by me, though it has 

 been alluded to by Naegeli. 



It has been repeatedly observed in various instances that 

 according to the evidence of plasmolysis the connection be- 

 tween the protoplasm and free cell walls is as close as between 

 the protoplasm and walls separating contiguous cells ; also it 

 has been seen, in the one example investigated in connection 

 with that point, that there was no evidence to show any 

 special relation between the protoplasm and pits of an ordinary 

 parenchymatous tissue [this will of course require confirmation 

 in other cases]. From these results it may be inferred that 

 the phenomena observed are due to a close mode of connec- 

 tion between protoplasm and cell wall, which is uniform 

 wherever they are in contact with one another in the living 

 cell. In the light of recent observations on the mode of for- 

 mation and growth of cell walls by apposition and coalescence 

 of microsomata, the connection thus demonstrated by plasmo- 

 lysis acquires a special interest. Unfortunately, the kernel of 

 the whole matter, viz. the ultimate mode of application of the 

 protoplasm to the cell wall, cannot be arrived at with cer- 

 tainty by plasmolysis, owing to the obvious difficulties of 

 observation of minute details with high powers in uninjured 

 cells. Still, collateral evidence may be gained, and as such I 



regard the observations above described, 

 o 



I would suggest two possible explanations of the phenomena 

 observed in plasmolysis, and their bearing upon the ultimate 

 mode of application of protoplasm to cell wall — (1) that the 

 main mass of protoplasm on retreating may leave the cell wall 

 still completely lined with a thin film of protoplasm ; {2) that 

 the peripheral part of the protoplasm being entangled, as a 

 network, among the deposited microsomata may, on the con 

 traction of the main mass, be drawn out at the points of 

 entanglement, into fine strings like those observed, while the 



