2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I ID 



reducing substance was measured after clearing the aqueous solutions 

 by treatment with neutral lead acetate and potassium oxalate. In 

 others, only the fermentable reducing substance was determined, from 

 the difference between analyses before and after treatment of the un- 

 cleared solutions with various yeasts.^ In either case sugar was re- 

 sponsible for all, or very nearly all, the reducing power found and, 

 as shown by the fermentation tests, consisted practically entirely of 

 glucose or fructose, or both. 



Table i. — Influence of illumination on reducing sugar content of etiolated 



seedlings 



Mgm. glucose equivalents 

 Illumination per gm. fresh weight 



Age Intensity Duration 



Exp. Species (days) (f. c.) (min.) 



I . . . Hordeum inilgare 



var. Hannchen 6 20 60 



22.4° 22.3" 



23.8 23.8 



" Mgm. sucrose per gm. tissue. 

 •> Leaf blades only. 



In a few experiments sucrose also was estimated from the increase 

 in reducing power after hydrolysis by invertase. 



Table i summarizes the results obtained with seedlings such as had 

 been found previously to exhibit increased carbon dioxide production 

 after illumination. Each figure represents the average of two or three 

 lots of plants. The values are expressed in terms of fresh weight of 

 tissue. Substantially the same relative results were found if calcu- 

 lated on the basis of dry weight of the extracted tissue. 



The data show that, under the experimental conditions employed, 

 the content of reducing sugar is not increased by illumination. Hence 



3 We are indebted to Dr. Lynferd J. Wickerham, of the Northern Regional 

 Research Laboratory, U.S.D.A., for cultures of yeasts with specific fermentative 

 ability. 



