ON PLASMOLYSIS. 157 



form the upper and lower surfaces of the prothallus. As far as 

 I was able to judge, they run as a rule in just as large 

 numbers to the free walls as to the walls separating con- 

 tiguous cells. 



It may often be seen that strings appear to cross one 

 another, as in the lower cell in fig. 1, This appearance may 

 be explained by reference to the protoplasmic body, which will 

 in such cases be found to have contracted irregularly. It may 

 also be seen that strings, which thus cross one another, are 

 not in the same plane, a conclusion which might easily be 

 drawn from fig. 1. Where, as in other cells of fig. 1, the con- 

 traction goes on more regularly, such crossing of the strings is 

 not seen. 



Remembering Strasburger's observations on the formation of 

 the walls in cell division, as well as the results obtained by 

 Tangl and Gardiner, it was of course a matter of interest to 

 observe whether these strings in two contiguous cells are 

 opposite to one another, and thus point to a direct continuity 

 of protoplasm through the walls, or whether this is not the 

 case. In many instances it does appear that the strings on 

 opposite sides of a wall are attached at corresponding opposite 

 points ; in a much greater proportion of cases, however, they 

 appear to have no relation to one another, but to be distributed 

 quite independently over the walls. It should be remembered 

 in connection with this that the strings run with equal fre- 

 quency to the free walls, and to those separating contiguous 

 cells. 



Such connection of the contracted protoplasm with the cell 

 wall, as that above described, is found to exist in the cells 

 throughout the prothallus. It has been observed in the cells 

 at the extreme growing point in young prothalli, and also in 

 the root hairs at points close to their apex. In such cells, 

 however, the phenomenon is not so well marked as in cells of 

 medium age, the threads being of finer texture. 



That these connecting strings consist of protoplasmic sub- 

 stance can hardly be doubted from their mode of origin and 

 their properties to be detailed below ; the application of re- 



