ON PLASMOLYSIS. 167 



trate the cell walls (i, e. in sieve plates) it still may retain its 

 connection with the cell wall after contraction by means of a 

 number of strings, which run severally to the pores of the 

 sieve (De Bary, ' Vergl. Anat.,' figs. 72, 75). These, if the 

 second explanation of the above phenomena were true, would 

 diiFer in degree but not in kind from the strings of protoplasm 

 observed on plasmolysis. It is probable, from Gardiner's 

 account (1. c), that the same may be the case in the perforated 

 pits in the cells of the pulvini on which he has worked. 



I have already stated that on careful observation of the 

 terminal parts of the strings soon after plasmolysis in the pro- 

 thallus they are often seen to split up close to the cell wall into 

 fine branches, and that they are thus attached to the cell wall 

 at a number of points. This observation gives still further 

 support to the second mode of explanation of these phenomena 

 of plasmolysis. 



Though it is impossible at present to decide with certainty 

 which of these interpretations of the phenomena is nearer the 

 truth, the latter seems to me to coincide best with the facts. 



It is unfortunately hardly to be anticipated that the phe- 

 nomena of plasmolysis will yield us any very certain conclusions 

 as to the ultimate structural relations between cell wall and 

 protoplasm, since the difficulties are so great in using high 

 powers on objects at least as thick as one whole cell; and it is 

 only by the use of high powers that this point can be decided. 

 We must, therefore, look to the study of fine sections for 

 further and secure information on this most important 

 question. 



