396 VEGETABLE PHYSIOLOGY 







during natural life the plant is receiving coincidently several 

 kinds of stimulation, the effect of some being not infre- 

 quently antagonistic to that of others. It is not easy to 

 discriminate between these, nor to say how the influence of 

 each helps to determine the resultant response. This is the 

 more difficult as not only the stimuli themselves but their 

 relative potencies differ continually. 



