﻿302 BOTANICAL GAZETTE [apkil 



flasks, stoppered with cotton. Controls watered with Knop's 

 solution were run. All of the solutions tested proved toxic, but 

 2A was found to be less toxic to corn under these conditions than 

 the others. The toxicity of the solutions was shown in the injury 

 to the root tips, causing a great decrease in the total length of root 

 produced as compared with the controls, and thus eventually 

 killing the plants. 



The effect of the 8 solutions listed in table I was tried on un- 

 sterilized alfalfa in sand. They were all found extremely toxic, 

 many of the plants dying as they emerged from the sand, and the 

 best of them attaining only one-fifth of the height attained by 

 controls watered with tap water. 



It was found by tests that tomato seeds did not germinate at 

 all in solution iA in sand, while controls in sand watered with tap 

 water grew vigorously. 



An attempt was made to secure sterile cultures of corn in 500 cc. 

 Erlenmeyer flasks in order to determine whether the presence of 

 organisms in the cultures was a factor in the toxicity of these cul- 

 tures. The sterility of the cultures was tested by making bouillon 

 cultures from various portions of the sand and the seeds at the end 

 of the experiment; 65 per cent of the cultures proved sterile. 



Three problems were to be solved in working out a method of 

 securing sterile cultures of seed plants: (1) the sterilization of the 

 flasks and contents; (2) the sterilization of the seeds; (3) the 

 transfer of the sterile seeds to the sterile flasks under sterile 

 conditions. 



The cotton-stoppered flasks, containing 200 cc. of sand and 

 20 cc. of the solution, were sterilized for 1 hour at 15 lbs. pressure 

 in the autoclave. A solution of silver nitrate was used as a means 

 of sterilizing the seeds. It was found by experiment that corn 

 would germinate well after treatment for 1 minute with N/30 0 

 AgN0 3 and subsequent washing with water. As a means of mak- 

 ing the transfer of the seeds to the flask, the box previously used by 

 Jensen (na) was used. When the lid of the box was closed, 

 the operator could thrust his hands into the gloves and work 

 without danger of contaminating the cultures from any source 

 outside of the box. Since the entire top and part of the front of 



