1898] PHYSIOLOGICAL ACTION OF PLASMOLYZING AGENTS 415 
cardinal numerical relations which have served as a basis for the 
discussion. In this diagram, # stands beneath the concentration 
just beginning to call forth plasmolysis; ¢ beneath the concen- 
tration representing the theoretical boundary concentration; e¢ 
beneath the concentration experimentally determined to be the 
boundary concentration, 
In view of the results above presented, it appears that plants 
may be fatally affected both by solutions acting osmotically and 
by solutions acting through their chemical properties. 
In the case of solutions acting osmotically and by this 
method causing death, it should be pointed out that while 
osmosis furnishes the means, the operation of which leads to a 
fatal outcome, chemical processes may very well be here involved, 
One may imagine that the attraction of the sugar molecules for 
water results in the removal of water more or less rapidly from 
the organism enclosed within the cell wall. At first, as the cell 
sap is relatively dilute, it parts with its water to the larger mass 
of plasmolytic solution without at a relatively rapid rate. The 
substances dissolved in the cell sap not being yielded up, the 
cell sap concentration rises. If this process does not continue 
beyond a certain point, the organism is able, when osmotic equi- 
librium is reached, to retain enough water to preserve its organ- 
ization and to sustain for weeks, or even months, a quiescent 
existence. If, however, an equilibrium between the cell sap and 
the surrounding medium is not reached until the water necessary 
to the maintenance of the integrity of the substance and of the 
processes of life is encroached upon, death must result and prob- 
ably in the last analysis through chemical changes. Hence, one 
may imagine that cane sugar in a solution of too great concen- 
tration in time will kill the cell through its interference with the 
chemical integrity of the substance or processes of the cell 
exerted along the lines of osmotic activity. 
In the case of the other compounds working through their 
toxic Properties, the penetration of the substance into the cell is 
probably followed more or less promptly by chemical changes 
due to interference with the compounds essential to life, and 
