304 Transactions of thk Canadian Institute. [Vol. VII. 



as is proved by testing the leaf for the salt taken up by the petiole. The 

 cells of the leaves having the " water-logged " appearance are plasmo- 

 lyzed, showing that water has been extracted osmotically by the salt. 

 This phenomenon is mentioned by V^ines (p. 40). 



Certain solutions will, therefore, if applied to the cut ends of the 

 petioles, kill the leaves by extracting water from the cells. This effect 

 is not so rapid as might be expected, because the solution which ascends 

 the petiole and enters the leaf, is not of the same concentration as that 

 supplied in the test-tube. This fact is not as yet generally known to 

 botanists, because in the experiment to demonstrate the rate of ascent 

 of sap in plants, a solution of a lithium salt is taken, and the distance of 

 ascent is determined at any given time by the height of the lithium salt. 

 It is known that the experiment with eosin is not accurate, for the 

 reason that the water ascends faster than the eosin. What is true of 

 eosin is true of lithium, and probably of any other solution, as may be 

 demonstrated as follows : — Saturate a piece of filter paper with a solution 

 of potass-sulpho-cyanide, allow it to dry, then place one end of the 

 paper in a solution of ferric chloride. As the iron solution ascends, the 

 height of the solution is indicated b}' the deep brown-red colour, formed 

 where the salts meet, in consequence of the chemical action between 

 them. A zone of water may be seen to advance ahead of the substance 

 in solution by the translucent effect which it produces upon the paper. 

 The difference between the height of solution and the height of this 

 zone of water at any given time is considerable, as is the case with eosin 

 and other coloured solutions. In the case of lithium it can not be seen 

 because the solution is colourless, but it acts as other salts do, as has 

 been shown by experiment (Fig. 9). 



In Detmer and Moor (p. 233) it is stated that the lithium ascends as 

 high as the water does in which it is dissolved. This is not opposed to 

 the ground taken by the writer, namely, that lithium in solution does 

 not ascend as rapidly as the water. This has been proved by the writer 

 by cutting the strip of absorbent paper just below the point reached by 

 the water while the water is asce^iding and before it has reached its 

 maximum height. This portion of absorbent paper contains no lithium. 

 Sachs' view was that a decomposition of the lithium must result if the 

 water ascended higher than the lithium salt, for he says (p. 236) : — " The 

 lithium solution possesses, as I convinced myself with the aid of the 

 paper .strips previously mentioned, the advantageous property of 

 ascending without being decomposedr 



The present view of the lithium test for the rate of ascent of water is 

 based chiefly upon work done in 1877 by Sachs' (1878, p. 165). He 



