18 Lewis Knudson 



were of another form, as described later. The use of large tubes is 

 shown in figure 1. 



Fig. 1. METHOD OF GROWING PLANTS IN LARGE CULTURE TUBES 



NUTRIENT SOLUTION 



The plants were grown for the most part within the tubes or cylinders 

 On an agar medium to which were added the nutrient solution and the 

 carbohydrate whose influence was to be studied. Pfeffer's solution was 

 employed, though of a weaker concentration than usual. The solution was 

 made according to the following formula: 



Calcium nitrate 4.0 grams 



Potassium nitrate 1.0 gram 



Potassium chloride 0.5 gram 



Potassium phosphate (dibasic) 1.0 gram 



Magnesium sulfate 1.0 gram 



Ferric chloride 4.0 milhgrams 



, Distilled water 12.0 liters 



ACTION OF SOLUTION ON DISACCHARIDES 



The inverting action of the nutrient solution on saccharose, maltose, 

 and lactose was tested and found to be without effect. There was of 

 course no hydrolyzing action on the agar. 



