332 MICROCHEMISTRY OF PLANT PRODUCTS 



partially dissolved. A solution of 2 gm. of purest potassium 

 hydrate in 100 gm. of water dissolves small crystals within two 

 hours, while the solution of larger crystals requires a longer time. 

 A solution of iodine, prepared as directed on page 311, colors 

 the crystals dark brown. A 25 per cent, solution of hydrochloric 

 acid dissolves large and small crystals immediately. When this 

 solution is diluted with 4 parts of water, it takes on a brownish- 

 red color with the iodine solution. When i drop of malt extract 

 is added to 5 drops of a neutral solution of amylodextrine this 

 becomes inverted within 10 minutes, so that it no longer is colored 

 by the iodine solution. To prepare the malt extract treat i 

 part of malt with 3 parts of water and filter the solution. The 

 solution of crystals of amylodextrine by the malt extract requires 

 several days. At a temperature of 40° C. saliva dissolves the 

 amylodextrine crystals within forty-eight hours. To prepare the 

 saliva, mix human saliva with a drop of chloroform, filter, and 

 preserve over a few drops of chloroform. 



Amyloid. — This carbohydrate occurs as reserve material in 

 the seeds of Tropaolum majus, Impatiens balsamina, PtBonia 

 officinalis, and in many other plants. It is colored blue by 

 dilute solution of iodine, but with a concentrated solution it 

 is colored a brownish-orange. It is soluble in cuprammonia 

 only after a day. Treated with a 30 per cent, solution of nitric 

 acid it swells strongly, and finally dissolves. This is different 

 from the amyloid produced by the action of acids and certain 

 chlorides on cellulose. 



Amylose. — Starch grains which are colored blue by iodine 

 — that is, most starch grains — are, according to Meyer, com- 

 posed of crystals of two kinds of amylose, named by Meyer 

 a-amylose and /?-amylose. The a-amylose has been isolated 

 in crystalline form, but the /^-amylose has not been isolated, 

 and its microchemical behavior has only been determined 

 by experiments with starch grains. The microchemical behavior 

 of the a-amylose is as follows, the reagents being prepared 

 as directed under amylodextrine: Water at from 60° to 100° 

 C. does not soon dissolve the crystals of this amylose. Treat- 



