188 Plant Physiology 



completely renewed. For such a period of growth the 

 seeds of the pea carry a fairly adequate supply of the other 

 nutrients. Again, the seed is relatively rich in magnesium, 

 so that the omission of this element affects growth very 

 slightly, while the same fact emphasizes the need of cal- 

 cium in the solution. 



103. Other nutrient bases and antitoxic action. The 

 neutralizing action of various bases upon one another 

 has been demonstrated by Loeb, Kearney, Osterhout, 

 and others. In this regard calcium is most important. 

 At suitable concentrations it reduces the toxicity of delete- 

 rious solutions containing either potassium, sodium, or 

 ammonium, as well as of certain nonnutrient bases. 



The table on the opposite page includes data furnished 

 by McCool 1 from two distinct series of cultures with the 

 Canada field pea grown 30 days. 



In the first series the concentration of sodium employed 

 shows no growth whatever, and the addition of one 

 fortieth as much calcium gives a very considerable growth ; 

 therefore, a marked antitoxic effect. The best growth 

 occurs where the stronger concentrations of calcium are 

 used with the sodium, so that there appears to be a slight 

 mutual antagonistic action with respect to peas. The 

 strong effect of calcium upon the relatively toxic ammo- 

 nium salt is apparent. 



In general, all of the nutrient bases show a series of rela- 

 tions with respect to toxic action upon plants. For each 

 base the relations may be different, and a certain varia- 

 bility is to be accounted for by differences in the composi- 



1 The experiments of which these constitute a small part will be pub- 

 lished as a bulletin of the Cornell Experiment Station. 



