26 Martin J. Prucha 



EXPERIMENT 5 



INFLUENCE OF VARIOUS CONCENTRATIONS OF PFEFFER's SOLUTION, BOTH 

 WITH AND WITHOUT NITRATES 



Wide-mouth bottles of 500 cubic centimeters capacity were used in 

 this experiment. They were all covered with black paper. Two series 

 were prepared, one with Pfeffer's full nutrient solution and the other 

 with Pfeffer's solution in which the nitrates were replaced by the chlorides 

 of the same metals. The following concentrations in each series were 

 employed, takmg the concentration of the full nutrient as 1: ^q, |, I, \, 

 1, 2, 3, 4, and 8. Five plants were growm in each bottle, and all were 

 inoculated. The duration of the experiment was three weeks. 



Results. 



In the full nutrient solution a few nodules developed in the jig concen- 

 tration. In the other concentrations no nodules appeared within the three 

 weeks. 



In the nitrate- free solution nodules developed best in concentration 1. 

 In the I and \ concentrations a few nodules appeared. 



EXPERIMENT 6 



INFLUENCE OF PFEFFEr's SOLUTION IN WHICH THE ESSENTIAL ELEMENTS 



WERE ABSENT 



In this experiment the same vessels were used as in experiment 5. 

 The solutions were prepared as follows: 



^ , ^. . .^ f Ca(N03)2 was replaced by CaCl2 



h or solution minus nitrogen \ -r^^' i i i -.^r^^ 



^ \ KNO3 was replaced by KCl 



fKNOs was replaced by NaNOs 

 For solution minus potassium \ KH2PO4 was replaced by NaH2P04 



[KCI was replaced by NaCl 

 For solution minus phosphorus, KH2PO4 was replaced by NaH2P04 

 For solution minus sulfur, MgS04 was replaced by MgCl2 

 For solution minus magnesium, MgS04 was replaced by MgCl2 

 For solution minus iron, FeCls was replaced by NaCl 



One plant was grown in each bottle. The plants were examined three 

 weeks after planting. 



