THE PERMEABILITY OF PROTOPLASM 



127 



Though Osterhout illustrated this quantitative method 

 by data obtained by the measurement of the roots of wheat 

 seedlings, this might have been equally well done by 

 measurements of electrical resistances of tissues and their 

 alterations in isotoxic salt solutions of various composi- 

 tion. The underlying phenomena of all such experiments 

 are alterations in the permeability of the protoplasm, 



~ Pure water. n 



G 



A 100 

 B o 



50 

 50 



0% 

 100% 



FIG. 12. DIAGRAM REPRESENTING THE COMPOSITION OP SOLUTIONS. 

 (This serves as a base of the solid model shown in Fig. 13.) 



The lowest line represents mixtures of solutions of two salts A and B ; 

 the line EF represents the same mixtures diluted with an equal 

 volume of water. Any line drawn parallel to EF will express th e 

 same mixtures diluted to a degree corresponding to the position of 

 the line. On the line CD all points represent distilled water. 



which by the constructions described in the preceding para- 

 graphs can now be expressed in a quantitative manner. 



The effect of variation of the concentration of the iso- 

 toxic solutions has also been studied by Osterhout (1914, 3). 

 The forms of the curves were found to become much natter 

 as dilution proceeded, but the proportions showing the 

 greatest degree of antagonism appear to remain practically 

 unaltered as shown in Fig. 11. To illustrate the results 



