Loss in percentage of original weight 
1918] LONG—DESICCATION AND RESPIRATION 357 
out at this laboratory that the oxidation of the organic acids result- 
ing from sugar katabolism is more rapid in the presence of light, and 
that these acids tend to accumulate in darkness. Soluble sugars 
in no. 23 have been burnt out almost completely, only traces 
being found in the expressed sap. If, as we have assumed, a high 
June 24 Dec. 24 June 24 Dec. 24 June 24 Dec. 14 
1914 1914 Igt5 IgI 1916 1916 
Fall Sunlight | Jarhness 
Fic. 1.—TIllustrating course of loss in weight of Echinocactus no. 23 from 
June 24, 1914, to January 23, 1917. 
concentration of soluble non-reducing sugars was present in the sap 
of no. 23 at the time when it was put into darkness, a very large 
destruction has taken place of sugars of this type. However, and 
this is an important point, the destruction of the stored insoluble 
polysaccharides seems hardly more than begun. A consideration of 
table I shows that the total hydrolyzable carbohydrate content of 
no. 23 after its prolonged stay in darkness is hardly less than that 
