1914] OSTERHOUT— ANTAGONISM CURVES 371 



by diluting the various mixtures. Such a model is shown in 



fig- 3- 



It may be desirable to add something concerning the compara- 

 tive amount of growth in distilled water and in balanced solutions. 

 When dilute solutions are employed, the maximum growth obtained 

 in a fully balanced solution may be greater than that in distilled 

 water, owing to the nutrient action of the solution. But when 

 strong solutions are employed, this is not the case, for the osmotic 

 pressure of the strong balanced solution will inhibit growth. 



In general, growth in strong solutions furnishes a much more 

 satisfactory criterion of antagonism than growth in weak solutions. 

 The inhibition of growth due to the osmotic pressure of the strong 

 solutions does not noticeably affect the form of the antagonism 

 curve, since it makes itself felt in the pure solutions to about the 

 same degree as in the mixtures. When we employ the method of 

 mixing equally toxic solutions, the osmotic disturbances are com- 

 pensated in a manner which has been previously discussed. 3 



Harvard University 



3Bot. Gaz. 58:178. 1914. 



