ON PLASMOLYSIS. 163 



Observations were also made on the cells of the amphigastria 

 of Lunularia and Marchan tia, a 2 per-cent. solution of salt 

 being found strong enough to induce plasmolysis. The proto- 

 plasm in these cells is very meagre; when contracted it was 

 seen to be connected with the cell wall by a few long, fine 

 strings of protoplasm. 



Filaments of Spirogyra were also treated with salt solu- 

 tions of various strengths {2, 5, and 10 per cent). The pro- 

 toplasm of each cell contracts into a rounded mass, usually 

 leaving the septa entirely, but often remaining in contact with 

 the lateral walls. Here also fine strings of protoplasm run 

 from the contracted mass to the walls, more especially to the 

 septa. They often have nodal thickenings, and execute 

 obvious vibratory movements. The phenomenon is better seen 

 on plasmolysis with 10 per cent, than with weaker solutions, 

 and even then it is seen only with diificulty. 



The above observations having been made npon cells with 

 approximately smooth walls, the question suggests itself, what 

 will be the relation of these strings of protoplasm to the 

 pits in walls where these are present ? Peculiar interest is 

 attached to this question since the publication of the obser- 

 vations of Gardiner on plasmolysis of pitted parenchymatous 

 cells of the pulvinus of Robinia pseudacacia, and other 

 plants, in which he had previously demonstrated the con- 

 tinuity of the protoplasm through the pits. 



The leaves of species of Trichomanes serve as excellent 

 material for the study of this point, since the lateral portions 

 of the lamina consist of a single layer of cells, of which the 

 walls separating contiguous cells are thick and have numerous 

 pits (fig. 7, A, b) ; the walls in these figures are represented as 

 rather thicker in proportion than they appear in nature. A 

 10 per-cent. solution of salt was found to give good results. 

 Here, as in other cases described, there is usually no very 

 obvious system of strings to be seen immediately after the 

 contraction of the protoplasm connecting it with the cell wall ; 

 but, as before, the intervening space soon assumes the silky 



