SUPPLEMENT 13 



51, 1. J, for p. 240 read p. 258 



52, 1. 24, /OP 1390 read 1038 



I. 28, /or and these . . . pressures read possibly the greatest pressure 



II. 50-2, for root which ... to pass read root also which excrete water with 

 like energy ; but since other cells, exposed to this pressure, also permit water 

 to filter through them, 



I. 53, for plus read versus 



53, 1. 3, for that bleeding- read that the bleeding- 



II. 5-10, for and so on ... conditions of bleeding read and that such regions 

 are not in uninterrupted communication with each other. Why intercom- 

 munication between two closely-related regions, e. g. in the xylem of a tree, 

 is not unrestricted we shall discover when we consider the external conditions 

 of bleeding (p. 54). 



54, 11. 16-19, for a much greater effect . . . Malays) ; read a much greater 

 stimulus is necessary, for the Malays, during the four or five weeks previous 

 to flowering, inflict repeated blows on the base of the bole with a wooden 

 hammer, and 



1. 40, delete whilst what may be termed . . . permeability of the proto- 

 plasm (P. 56, 1. 20). 



56, 11. 26-9, for In the uninjured plant . . . infliction of the wound read 

 In the uninjured plant, however, water is pressed into the vascular strand. 

 It is true we are often able to demonstrate this only after the infliction of the 

 wound ; 



1. 32, for made, read made ; in fact, conclusive proof of this is available. 



I. 51 P. 57, 1. 6, for In Colocasia . . . pure water read A complete picture 

 of the process as occurring in Colocasia has been furnished us by MOLISCH 

 (1903). In an immature leaf as many as 163 small drops were expressed per 

 minute, and with such force that they were shot out to some distance ; in older 

 leaves larger drops fell on the ground at the rate of 190 per minute. An 

 individual leaf may give off in a single night even 100 g. of water. In the 

 expressed fluid only traces of organic materials and ash were demonstrable. 



57, 1. 28, for Vicia sepium read Vicia Faba 

 last line, for deliminated read delimited 



58, 1. 19, for MOLISCH read MOLL 



59, 11. 1-2, for absorbing hygroscopic water read absorbing water hygroscopic- 

 ally 



II. 12-17, for There is practically . . . our present subject read Any attempt 

 to arrive at an explanation of the unilateral exudation of water from plant 

 cells (comp. PFEFFER, 1892) forces us to the belief that the phenomenon is 

 without doubt an osmotic one. It is evident, however, that we cannot or may 

 not attribute all the various instances to the same causes, for the product of 

 secretion varies from pure water to a quite concentrated sugar solution. Glanc- 

 ing first at those cells which produce sap which is extremely poor in materials, 

 we may assume that they possess protoplasm which is completely impermeable 

 to the substances dissolved in the vacuole, and the question then arises, How 

 can water be unilaterally expressed from such a turgescent cell ? In an 

 ordinary cell the incoming stream of water due to osmosis is, on all sides, 

 just as great as the outgoing stream induced by the counter-pressure of the 

 cell-wall (p. 13) ; should more water come out at some particular place 

 than enters there, then more must enter at some other place than comes out. 

 In order to explain this variation in behaviour of different sides of the cell it 



