



r 





1920] SCHLEY 



-GEO-PRESENTATION AND GEO-REACTION 75 



method (op. cit., pp. 52, 53.). An N/20 solution of permanga- 

 nate was used. A third 50 cc. portion of this clarified solution 

 was used for the determination of non-reducing or hydrolyzable 

 sugars. The hydrolysis was performed according to the method 

 for the determination of sucrose in the absence of raffinose (op. cit., 

 pp. 40, 41). The cooled solution was neutralized with 20 per cent 

 sodium hydrate, brought to 100 cc. volume, and duplicate sugar 

 estimations made of 50 cc. portions as described. 



The residue (F 2 ), after the determination of the dry weight (to 

 be described later), was used for the determination of the poly- 

 saccharides according to the method for direct acid hydrolysis of 

 starch (op. cit., p. 53). Duplicate determinations of 50 cc. portions 

 were used for the determination of sugars, as in F z . 



The calculations were based on the milligrams of copper oxi- 

 dized in the change from cuprous to cupric oxide, and expressed in 

 equivalent milligrams of dextrose obtained from the Munson and 



Walker table accompanying the method of analysis (p. 243). 



The portion of F x for the determination of dry weight was evapo- 

 rated to moist dryness on the steam bath and brought to constant 

 weight in vacuo. The dry weight of F 2 was obtained by bringing 

 the residue of the original tissue to constant weight in the electric 

 oven at a temperature of 104 C. The calculations for both were 

 based on the dry weight per gram of the fresh material. 



The third portion of F x was used for the determination of the 

 total nitrogen. This determination was made after the Kjeldahl 

 method as modified by Arnold. Calculations were made on the 

 amount of nitrogen per gram of fresh weight. Table I shows the 

 results obtained. It will be noticed that the soluble sugars vary but 

 little throughout. The hydrolyzable sugars increase markedly at 

 the time of visible response, and are greater on the convex side. The 

 polysaccharides decrease as the hydrolyzable sugars increase. The 

 dry weight of F x remains practically constant. The dry weight of F 2 

 remains practically constant until the beginning of curvature, when 

 the weight of the convex side becomes less. The results of this sugar 

 determination are not comparable with the work of Kraus, for 

 he was working with the raw pressed sap, which probably contained 

 reducing substances other than sugars, as he himself suggests. 



