THE PERMEABILITY OF PROTOPLASM 123 



To represent the antagonism of mixtures of three salts, 

 Osterhout (1914, 2) made use of Rooseboom's method, 

 which is fully described in Findlay's " Phase Rule." It 

 consists in the construction of an equilateral triangle, each 

 side of which is made equal to 100 units. The apices 

 represent or 100 per cent, of one of the three com- 

 ponents. Thus a point on any side denotes a percentage 

 of a mixture of two substances, whereas a point inside 

 the triangle defines the composition of a mixture of all 



75 50 25 n 



uoo Nad 



CaCl 



FIG. 8. DIAGRAM REPRESENTING THE COMPOSITION OP VARIOUS MIX- 

 TURES OF THE CHLORIDES OF SODIUM, POTASSIUM, AND CALCIUM, 

 OBTAINED BY MIXING ISOTOXIC SOLUTIONS OF THE COMPONENTS 



The numerals refer to molecular percentages. This serves as the base 

 of the solid model shown in Fig. 9. 



three components. This is at once apparent on referring 

 to Fig. 8. Osterhout found that the roots of wheat grew 

 equally well in solutions of sodium chloride 0'12 M, potas- 

 sium chloride 0-13 M, and calcium chloride 0-164 M. The 

 apices of the triangle, C, B, and A, represent respectively 

 pure solutions of the salts of the above concentrations. 

 Thus G denotes a mixture of the chlorides of potassium 

 and sodium in which the molecular composition of the 

 first- mentioned salt is 75 per cent. 



