iyi6] RIGG—SOIL TOXINS 3°7 



be a possible factor in the lowering of toxicity on the addition of 

 sodium hydrate. 



The fact that the toxicity of solution iA was not destroyed by 

 the aeration here reported does not necessarily mean that the 

 toxicity cannot be removed by oxidation. 



The removal of the toxicity from solution iA by shaking it 

 with animal charcoal is probably to lie explained as an absorption 

 phenomenon. 



The only importance attaching to the toxicity of the soils 

 (preparations iD, 2D, and 3D) is that not all of the water-soluble 

 toxic materials had been washed out of them by the treatments 

 to which they had been subjected. 



The products of the decay of Nymphaea rhizomes are toxic, not 

 only to Sagittaria and Tradescantia, but also to agricultural plants. 

 Apparently the toxicity of solution iA to tomato, alfalfa, and corn 

 is in the order named. 



While the box used for transferring the sterile seeds to sterile 

 llask cultures is fairly efficient, the method is somewhat slow and 

 tedious, and it is believed that fairly good results may be obtained 

 without its use. It seems very desirable to extend our knowledge 

 of the growth of seed plants in the absence of other organisms. 



In the one case mentioned, the toxicity of the products of this 

 rhizome to corn seemed to be independent of the presence of organ- 

 isms, either at the time of dissolving the toxin from the rhizome, or 

 at the time of its action on the growing plants. 



The fact that the toxicity of solution iA, even when undiluted, 

 can be removed by precipitation with ammonium sulphate seems 

 to suggest that the presence of colloidal matter may be a consider- 

 able factor in toxicity of that solution. 



An alkaloid similar to nupharin is reported by Wehmer (28) in 

 the rhizome of N. alba. He also reports fat and organic acids. 

 These also represent possible factors in the toxicity. It seems 

 possible that the toxicity may be due partly to products formed 

 during decay and partly to products merely released by this decay. 



The toxicity of the water extract of the ash is possibly accounted 

 for on the basis of the presence of one or more basic substances. 

 Wehmer states that the rhizome of Nymphaea alba contains 



