364 Carho/ii/(fndex of (/ic Leaf of the Pottdo 



The total dextrose corresponding with leaf material taken 



200 250 

 = 0-00443 X -— X ;^" = 0-0296 grm. 

 50 150 ° 



The total maltose corresponding with leaf material taken 

 = 0-00586 X ^ X "^^ = 0-0391 grm. 



OU 101/ 



"Soluble starch" corresponding with dextrose 



= 0-0296 X 0-9 = 0-02664 grm. 

 "Soluble starch" corresponding with maltose 



= 0-0391 ^ 1-055 = 0-0371 „ 



Total = 0-0637 „ 



Percentage of "soluble starch" = ,^„ ,„^ x 100 = 0-65. 

 '^ 9-8405 



.'. Percentage of soluble starch on t.v.d.ji. in leaf 



0-65 X 102-42 ... 

 = = 0-41. 



161-67 



True starch. The leaf material remaining after the extraction with 

 water was gelatinised by heating with about 200 cc. of water during 

 30 minutes in boiling water; after cooUng, 0-1 grm. taka-tliastase was 

 added and 2 cc. of toluene and the mixture left 24 hours at 38", stirring 

 at intervals. Two drops of concentrated sodium hydroxide were then 

 added to destroy the enzyme and the solution filtered from the leaf 

 material on a Buchner funnel; this was thoroughly washed with 

 water by decantation until the total volume of the filtrate was about 

 475 cc. Basic lead acetate was then added (2-5 cc. was generally just 

 sufficient) and the volume made up to 500 cc. The slight excess of lead 

 in the filtrate was removed by adding e.ractJi/ the necessary i|uantity 

 of solid sodium carbonate and after filtering the reducing power and 

 rotation of the solution were determined. 



50 cc. gave 0-0908 grm. CuO 



Polarisation = 0-264° in 400 mm. tube at 20°. 



These values corrected for 0-1 grm. of taka-diastase under exactly similar 



conditions (CuO correction = 0-0138 grm.; polarisation = + 0-073' ) 



give 



Corrected CuO from .50 cc. = 0-0770 grm., 



Corrected polarisation = + 0-191°. 



