THE PHYSIOLOGICAL ACTION OF CERTAIN PLAS- 
MOLYZING AGENTS. 
RODNEY H. TRUE. 
INTRODUCTORY. 
In the course of an investigation in which the writer was con- 
cerned regarding the physiological action of certain sodium salts, 
various degrees of destructiveness were observed. In some of 
the weakest salts, it seemed possible that the osmotic action as 
well as the chemically harmful properties of the substances might 
play a réle, so concentrated were the solutions in which the test 
plants first survived. It seemed to be very desirable to analyze, 
if possible, the injurious physiological action of some of the com- 
moner and less harmful salts into its osmotic (physical) and toxic 
(chemical) components, should it appear that both contribute to 
the results seen. 
The desirability of some clearer understanding of the action 
of these substances seemed the greater by reason of the frequent 
USE as plasmolyzing agents to which certain of them have long 
been put by plant physiologists. Sodium chlorid and potassium 
nitrate, especially, have been much employed in this way. In 
thus using them, botanists have followed the lead of De Vries, 
(1) who first applied these substances in this way, and have 
assumed them to be essentially harmless, as asserted by De Vries 
(p. 12). He says, ‘‘Es ist eine sehr verbreitete irrthimliche 
Ansicht, dass concentrirte Salzlésungen (z. B., eine Kochsalz- 
lésung von 10~20 %) fiir des Leben der Pflanzenzelle gefahrlich 
seien,”’ Davenport (2) more recently says, “It is not easy to 
find a reagent of which we may be certain that it acts only 
°smotically. NaCl is probably more generally useful in this way 
than any other substance.” 
As far as the writer knows, no attempt has been made hith- 
siete to analyze thus the action of a substance, beyond the single 
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