38 



Lewis Knudson 



In the experiments with water cultures museum cyhnders 30 by 50 

 centimeters in size were used as culture vessels, each containing 50 cubic 

 centimeters of the nutrient solution to be tested. As a support for the 

 seedling each cylinder was provided with a perforated aluminum receptacle 

 (the lower part of a tea ball, the holes of which had been greatly enlarged) 

 suspended by a string just below the cotton plug with which the cylinder 

 was fitted. The whole was then sterilized in the autoclave. It was neces- 



FlG. 5. INFLUENCE OP SUGAR ON VETCH. WATER CULTURE 

 1, Saccharose; 2, fructose; 3, lactose; 4, check (no sugar); 5, glucose; 6, maltose 



sary to immerse the base of the cylinder in a pan of water in order to 

 avoid breakage during sterilization. Before sowing the seed the part of 

 the string on the outside was sterilized by moistening with calcium hypo- 

 chlorite solution and wiping with a piece of cotton saturated with alcohol. 

 The cotton plug and the string were then flamed. Moistening the string 

 with the calcium hypochlorite solution removed all danger of its burning, 

 and also aided in the sterihzation of the string. Two seeds were planted 

 in each receptacle, and the receptacles were then lowered so as to be just 



