276 EXPERIMENTS. [CH. XIV 



an accurate hydrometer, then equals the sp. gr. of the 

 potatoes. 



Tables shewing the p.c. by weight of dry starch in 

 potatoes, corresponding to different specific gravities, 

 have been constructed'! 



This method only applies to potato tubers. 



II. Compare the amount of starch in leaves of Acer 

 pseudoplatanus which have been collected on a warm 

 evening after bright day (and dried after killing with 

 chloroform) with the amount in leaves of the same species 

 collected early next morning and treated in same way. 



Use the method given in I. a. 



III. Determine the starch in grains of wheat : and in 

 grains of wheat which have germinated and been kept in 

 the dark for three days before killing. 



Use the method given in I. a. 



Let the grains germinate on damp sand, and after 

 keeping three days in the dark take whole plants (in- 

 cluding the residue of the grains), wash thoroughly, and 

 dry at 100° C. 



' See Chemiker-Kalender (1893, p. 377). 



