;,04 BOTANICAL GAZETTE [april 



The results showed that solutions iA, iB, iC, and 2A (these 

 were the only ones tried) are just as toxic under these con- 

 ditions as when organisms were known to be present in abundance. 

 Since 65 per cent of these cultures were shown (by bouillon cultures 

 from them at the close of the experiment) to be sterile, it is evident 

 that the presence of organisms is not a necessary condition of the 

 toxicity of these solutions. 



Solutions 1 A, iB, and iC likewise proved toxic to alfalfa in 

 cultures prepared as previously described for corn. The same 

 precautions for securing sterility were observed, but tests of sterility 

 were not made. 



The toxicity of solution 4A to Tradescantia cuttings was tested 

 as follows: wide-mouth 50 cc. bottles were filled with dilutions of 

 the following strength: 20, 15, and 10 per cent. Into each of 

 these was placed a cutting of Tradescantia. The mouths of the 

 bottles were left open. At the end of 16 days no root hairs had 

 formed on any of these plants and all of the plants were showing 

 signs of death. The controls in Lake Washington water all had 

 abundant root hairs and were in healthy condition. 



Other sets of bottles were prepared as previously described, 

 except that the mouths were stoppered with cotton and the bottles 

 containing the liquids were sterilized in the autoclave. The dilu- 

 tions were as follows: undiluted, 20, 15, and 10 per cent. Each 

 cotton stopper was then displaced just enough to allow a cutting 

 of Tradescantia to be placed in the liquid. None of these plants 

 developed normal root hairs. All of them except those in the 10 

 per cent dilution showed signs of death at the end of 16 days. 

 Turbidity due to the action of organisms was evident in all of these, 

 and molds grew on some of them. 



Flasks (500 cc.) were prepared, cotton-stoppered, each con- 

 taining iSogm. of sand and 18 cc. of solution. These were auto- 

 claved at 12 lbs. pressure for 1 hour. Solution 4A was used pure 

 and also in the following solutions: 20, 15, and 10 per cent. Con- 

 trols with tap water were also run. Corn was treated with N/100 

 silver nitrate for 2 minutes, then with sterile forceps 5 kernels were 

 placed in each flask. At the end of 16 days the growth was notice- 

 ably greater in all of the controls than in any of the solutions. All 



