rgi6] RIGG—SOIL TOXINS 3 QI 



The toxicity of the first 4 of these solutions when undiluted 

 was not perceptibly lowered by neutralization with sodium hydrate. 



A 20 per cent solution of iA was shaken in a large flask 5 times 

 a day for 10 minutes each time, for 3 days in order to aerate it, 

 and then filtered through a filter paper. Tests on Tradescantia 

 indicated that its toxicity was not decreased by this treatment. 



A 20 per cent solution of solution A in tap water was shaken 

 with animal charcoal and filtered. The filtrate was colorless and 

 odorless. The solution before this treatment had an amber color 

 and a foul odor. Cuttings of Tradescantia were placed in this. In 

 all cases they grew well and produced good roots with normal or 

 only slightly stunted root hairs. 



The animal charcoal with which this solution was shaken was 

 used as a soil for cultures of alfalfa seed. Controls of animal 

 charcoal shaken with tap water were run. The growth in the 

 controls was twice as great as the growth in the cultures. 



The toxicity of preparation 2D to Tradescantia cuttings was 

 tested by planting the cuttings in the preparation in small flower 

 pots. This preparation was further diluted also by grinding with 

 half its volume of sand. For convenience this further dilution is 

 referred to in table III as preparation 2Dx. Controls were run 



in potting soil. All of the pots in a set were placed together in a 

 large glass dish, so that they stood in about one-fourth of an inch 

 of tap water and thus were all watered alike. Table III shows the 

 results at the end of 14 days. 



Preparation 3D was tried in the same way with similar results. 

 Preparation iD was tried in the same way with corn and did not 

 prove toxic. Preparations 2D and 3D are not at all toxic to alfalfa. 



The toxicity of solutions iA, iB, iC, and 2A to unsterilized 

 corn was tested by planting the seeds in 200 cc. of sand watered 

 with 25 cc. of solution. The cultures were in 500 cc. Erlenmeyer 



