ON PLASMOLYSIS. 159 



on the movement of the nodal swellings from the main mass 

 of protoplasm. It may then be inferred that fresh substance 

 is derived from the main mass of protoplasm after the original 

 plasmolytic contraction. 



The question still remains, whether the increase in promi- 

 nence of the strings may not in part be due to lateral coale- 

 scence of originally separate strings. I have no direct 

 evidence that such coalescence does occur. Branching strings, 

 such as those represented in figs. 2, b, and 3, a, b, are often to 

 be found, which might appear to give colour to the idea that 

 the branches had originally been separate, and had subsequently 

 coalesced. It is, however, as far as my observations go, a 

 universal rule that the branching is in the direction of the 

 cell wall. This being the case, and taking into account the 

 process of drawing out of fresh material from the main mass 

 of protoplasm as above described, the following is a more pro- 

 bable explanation of such branchings. That two strings (or 

 more), originally separate but attached to the main body of 

 protoplasm at points very close to one another, had drawn out 

 from that body a common string on which they appear as 

 branches. Direct evidence that such a process does take place 

 is afforded by such objects as are represented in fig. 3, a and b. 

 In A are seen numerous strings, branched and unbranched, as 

 they appeared twenty minutes after plasraolysis. b represents 

 the same cell half an hour later ; only one of the most promi- 

 nent branched strings is drawn ; on comparing it with the 

 corresponding string in a it will readily be seen that the 

 change of appearance points to a process such as that above 

 suggested. The instances of branching, which are represented 

 in the figures, are only the last and roughest examples of the 

 process above described. On examining cells of prothalli 

 soon after plasmolysis with a high power (Hartnack, 13), 

 it was seen that not uncommonly strings, which appeared 

 single throughout the greater part of their length, branched 

 close to the cell wall, and were thus attached at a number 

 of points. 



It would appear, then, that the change, which gradually 



