NO. 2 SUGAR CONTENT OF SEEDLINGS — WEINTRAin AND I'klCE 3 



the observed stimulation of carbon dioxide evolution by lij^lit does not 

 appear to be attributable to increased sugar content. 



These results are not necessarily contradictory to those of I'arija 

 and Saran as the nature and condition of the plant material were quite 

 different in the two investigations. The sugar content of the detached 

 Aralia leaves was only about one-hundredth as great as in the week-old 

 grass seedlings, and it is not utilikely that metabolism follows a dif- 

 erent path under such a condition of star\ation. Oat seedlings grown 

 in dark-ness for a longer time (2 to 3 weeks) were found to exhibit a 

 rapid decline in reducing sugar and in some experiments showed ap- 

 preciable increases following illumination. This was the case also 

 with old detached tomato shoots which had been kept in the dark for 

 a few days. However, as such plants generally have an unhealthy ajj- 

 pearance and show a considerable degree of variability, the signifi- 

 cance of this finding is not clear and the experiments have not been 

 pursued. 



Suumtary. — Sugar analyses indicate that the increased rate of car- 

 bon dioxide production which follows illumination of etiolated barley 

 seedlings is not due to an increased content of reducing sugar or 

 sucrose. 



LITERATURE CITED 



Parija, p., and Saran, A. B. 



1934. The effect of light on the respiration of starved leaves. Ann. But., 

 vol. 48, pp. 347-354- 

 Shaiff.r, p. a., and Somogyi, M. 



1933- Copper-iodonietric reagents for sugar determination. Journ. Biol. 

 Giem., vol. 100, pp. 695-713. 

 Weintracb, R. L., and Johnston, E. S. 



1944. The influence of light and of carbon dioxide on the respiration ni 

 etiolated barley seedlings. Smithsonian Misc. Coll., vol. 104, Xu. 4. 



