﻿RIGG—SOIL TOXINS 



of the flasks except 2 (one control and one 15 per cent) had molds 

 growing in them. Bouillon and also agar cultures were made from 

 each of these, and the 1 5 per cent flask proved to be sterile. The 

 other was not sterile. These 2 flasks were kept a week longer and 

 the growth in the control was much better than that in the 15 

 per cent solution. 



The transfers of the corn in these cases were made in the labora- 

 tory, without the use of the sterile box just described. It is 

 hoped that by autoclaving the flasks at a higher pressure, and treat- 

 ing the seeds with the silver nitrate for a longer period, a larger 

 number of sterile flasks could be obtained. 



Solution iA was filtered and the fresh filtrate was immediately 

 saturated with ammonium sulphate. The sulphate was added 

 gradually and the solution was shaken after each addition. No 

 precipitate appeared at once, but when it had stood over night a 

 considerable amount of a brownish precipitate was present. Some 

 of the precipitate was at the surface of the liquid, some had settled 

 to the bottom, and some particles were in suspension in the liquid. 



The precipitate was filtered off and redissolved in a volume 

 of Cedar River water equal to the original volume of the solution. 

 Both filtrate and precipitate were then dialyzed in dialyzing tubing 

 in running water for 1 1 days. At the end of this time they showed 

 no precipitate with barium chloride. The filtrate and the pre- 

 cipitate were then tested for toxicity by placing Tradescantia 

 cuttings in them. Root hairs were formed in both, but their 

 development was poorer in the solution of the precipitate than 

 in the filtrate. 



In preparing solution 5A, 2 . 83 gm. of ash were obtained from 

 500 gm. of fresh rhizomes. This is 4. 7 per cent of the dry weight. 

 Approximately half of this went into solution when shaken with 

 800 cc. of Cedar River water at 18 0 C. The solution was basic 

 to litmus. In all cases tried with 5A and its duplicates the toxicity 

 to Tradescantia cuttings was so marked that practically no root 

 hairs developed and the plants soon died. When dilutions were 

 tried it was found that all dilutions down to 10 per cent (10 cc. 

 solution to 90 cc. water) inhibited root hair production; in 5 per 

 cent dilution root hairs developed normally. 



