l82 



BOTANICAL GAZETTE 



[august 



As an illustration of this method the results given in table I may 

 be cited. In this case the growth in the various mixtures was in 

 part determined directly and in part was calculated from results 

 obtained by growing plants in mixtures having almost the same 

 composition as the solutions given in the table, 



TABLE I 



Mixtures of equally toxic solutions 



Wheat (growth during 30 days) (XaCl 0.12M + CaCl 2 o . 164 M) 



Culture solution 



Aggregate length of 



roots per plant 



in mm. 



Additive effect 



CaCl 



75 per cent CaCl 2 



25 

 5° 



25 



75 



15 

 85 



5 

 95 



U 



u 



« 



» 



.. 



.. 



99 

 NaCl 



.» 



u 



NaCl 



CaCL 

 NaCl 



CaCl 2 



NaCl 



CaCl 2 

 NaCl. 



CaCl 2 

 NaCl. 



CaCU 



NaCl 



Antagonism 





55 



oo 



00 



105-55 



55 



0.91 



180 



00 



55 



2.27 



55 



oo 



00 



00 



55 



298 



00 



55 



37Q — 55 

 55 



435-55 



55 



300— 55 

 55 



4.42 



5-73 



6.91 



4-45 



The percentages refer to molecular proportions; that is, 75 per cent CaCl2+25 P" cent ^ a C* 

 means a solution in which 75 per cent of the dissolved molecules are CaCli and 25 per cent are NaCl. 



We may now consider the effect of mixing 



are not equally toxic. 



M 



M 



mixing 



same as mixing 



M with another solution of A iust twice 



words would be the same as increasing the concentration of A . In 

 this case the curve expressing purely additive effects would not be 



line, but would assume the form 

 to the horizontal axis, similar to VSW 

 from the curves given by Magowan 2 sh 

 tions of various concentrations. 



This is evident 



a B0T. GAZ. 45:45. 1908. 





