QUANTITATIVE CRITERIA OF ANTAGONISM 



W. J. V. OSTERHOTJT 



(with four figures) 



from 



freq 



It often happens 



in critical cases whether antagonism exists or 



antagonism 

 make use c 



permit 



r of antagonism becomes more 



character it becomes necessary 



denned standards by which 



be measured. Failure to 



may 



A 100 

 B 



15 



50 



25 



> misconceptions, 

 example of this the following 

 be cited. Suppose a solution 



of a toxic salt, A, to 

 be mixed with a solu- 

 tion of another salt, 

 B, the solutions 

 having the same 

 molecular concentra- 

 tion and the same 

 degree of toxicity. 

 Suppose that in 

 mixture of ioo cc. 



a 







25 



50 



75 



100% 



Fig. i. 



o.i M solution of A 

 plus ioo cc. of o.i M 



Curves showing the growth of roots in solution of B, plants 

 nuAiuics ui equally toxic solutions of two salts A and , than in 



B: the ordinates represent growth; the abscissas repre- grow better tnan 



either of the pure 

 solutions. Some in- 



mixtures 



sent the composition of the mixtures, thus A 50, B 50 



means a mixture in which the dissolved molecules are 



50 per cent A and 50 per cent B; the horizontal dotted 



line (LJM) represents the growth which would occur if vestigatOTS assert 



there were no antagonism (additive effect) ; LKM is the flio t this increase of 



antagonism curve; IBM, curve expressing increased , . ■> 



toxicity (opposite of antagonism); the quantitative growth should not De 



expression of antagonism at the point E is ~. attributed wholly to 



JE . a 



Botanical Gazette, vol. 58] I 178 



