120 



PLANT PHYSIOLOGY 



the maximum antagonism the salts must be in the proper propor- 

 tions. 



From the above table it is seen that, to produce the best results, 

 the two chlorides of sodium and calcium, which are equally toxic 

 when used alone, must be mixed in the proportions of 95 parts of 

 sodium chloride to 5 of calcium chloride. 

 #res. 



150 - 



100 



200 400 600 800 min. 



Fig. 7. — Illustrating antagonism. Curve A shows the change in resistance 

 of Laminaria tissue in pure CaCl 2 . Curve B shows the change induced by a 

 pure solution of NaCl. Curve C indicates what happens in a solution of 97.5 

 parts of NaCl and 2.5 of CaCl 2 . The dotted line indicates the condition in 

 sea water. (After data of Osterhout.) 



Working over a long period of time with many kinds of tissue, 

 Osterhout concluded that these antagonistic effects were con- 

 nected with changes which the salts produced upon the permeabil- 

 ity of the cell. In a previous chapter, the plasma membrane has 

 been mentioned as that outer surface of the cell protoplasm which 

 lies next to the cell wall. Before any salt can affect the cell it 



