20 



found during the determination of total solids of the sap {vide supra), 

 when the residue from this sap was of greater weight and charred at a 

 lower temperature than that of the check. 



The comparative optical rotations* and copper-reducing powers of 

 sap from "check" sections and those which had received applications of 

 potassium sulfate are shown in Table XV. 



Table XV.^Optical Rotation and Cu-Reducing Power of Sap Solutions. 



Rotation 

 circ. degrees. 



Reducing power. 

 Mft. CuO. 



Date. 

 1-9-15° 



2-IO-15 



2-17-15 



3-9-15 



Treatment. 



check 

 125 K 

 250 K 

 500 K 

 check 

 K 

 check 

 250-500 K 

 check 

 250-500 K 



Orig. 



0.73 

 1. 91 

 1.42 

 1.49 

 3 23 

 3-51 

 2.81 

 3.26 



2.43 

 3 00 



Hydrolyzed.^ Complete.* Orig. 

 0.83 



1.25 



0.97 



I .21 



Clerget. Comp 



I .20 



1-35 



1-53 

 2.28 



1-43 

 1. 91 



67 

 79 

 06 

 34 



556 

 476.5 

 521 

 522 



1434 

 1461 



1276 



1273 



1654 

 1976 



(1282) 



1438 



In view of the work of Davis, Daish and Sawyer,^ it seems possible, 

 though not proven, that the quantitative relationships of the sugars 

 in expressed sap may not represent the condition within the living tissue. 

 The consistently higher values obtained by both methods of estimation, 

 showed, however, that the application of potash to the soil had resulted 

 in an increased carbohydrate production, in a more rapid hydrolysis of 

 starch, or in a greater permeability of the cell membranes in the meso- 

 phyll tissue, so that a larger amount of sugar was found within the conduc- 

 ing and storage tissues. 



Leaf tissue (Set 2-10-15) dried at 50-70° was extracted with 80% 

 alcohol (i g. pptd. CaCOs being added to neutralize acids present) and 

 the extracts, after removal of alcohol, cleared with 5 cc. neutral lead ace- 

 tate, I cc. basic lead acetate and alumina cream. The extracts from 7 g 



* A. Schmidt and Hausch half-shadow polariscope, with tubes 4 dm. long, was 

 used. CuO values were obtained by using Defren's^" solution, the copper being de- 

 termined by Low's method (Treadwell and Hall, p. 682). 



" 5 cc. sap diluted to 50 cc. cleared with 5 cc. basic lead acetate (sp. gr. 1.115) 

 and an excess of alumina cream. 



* 20 cc. sap diluted to 100 cc. cleared with 10 cc. basic lead acetate and alumina 

 cream. 



* 10 cc. sap diluted to 100 cc. with 5 cc. basic lead acetate and alumina cream. 

 ■^ 10 cc. sap diluted to 100 cc. with 2 cc. basic lead acetate and alumina cream. 



* Hydrolyzed 24 hours with 10% 0.5 N HCl at 70°. 

 ^ Clerget inversion. 



' Inversion for 3 hours in boiling water bath of 25 cc. soln. 12V2 cc. water and 

 2.5 cc. HCl sp. gr. 1. 19. 



