464 



BOTANICAL GAZETTE 



[DECEMBER 



In the third experiment the procedure was similar to that in 

 the preceding experiments. A white dent corn was used, and also 

 Canada field pea. In addition to using Pfeffer's solution plus 

 soluble starch, a number of cultures were made in which Pfeffer's 

 solution alone was employed, to see whether any reducing sugars 

 were secreted. Two liter flasks were used. The concentration of 

 starch was approximately 0.35 per cent. The duration of the 



TABLE I 



experiment was 47 days. At the conclusion of the experiment, 

 the culture solution and the controls were made up to their original 

 volumes, and 20 cc. portions were taken and were analyzed by 

 Shaffer's method (6) for reducing sugars. Sample lots of each 

 were also incubated with 2 per cent of toluene at 32° C. for 10 days, 

 and the reducing sugars again determined. The data are given in 

 table II. 



There is a very slight increase in reducing sugars in some of the 

 culture solutions over that in the control, but not enough to be of 

 any significance. Furthermore, after 10 days' incubation there was 

 no increase in the amount of reducing sugars. 



Finally, to prove that the soluble starch is not utilized directly 

 or indirectly to any appreciable extent, the following procedure was 

 undertaken. Sample lots of the control and culture solutions were 

 hydrolyzed and reducing sugars were determined. It was found 

 that the control and culture solutions showed the same amount of 



