THE RESERVE MATERIALS OF PLANTS. 69 



by being soluble in saturated solutions of sodium chloride. 

 Its globulin character is established by the fact that it is 

 insoluble in water, but has the power of dissolving in weak 

 saline solutions. It can be precipitated from the latter by 

 large dilution or by dialysis ; also by saturation of the 

 solution by magnesic sulphate or amnionic sulphate. It 

 shows a peculiarity in its relation to heat, being precipitated 

 on boiling its solution, but in not being at that temperature 

 converted into coagulated proteid. Wheat flour contains 

 about *6 to 7 per cent, of edestin. 



The albumin has been named leucosin ; it is present in 

 less quantity than edestin, about "3 to "4 per cent, being 

 obtainable from the flour. Its reactions show certain 

 peculiarities ; it is, unlike most albumins, precipitated by 

 saturating its solutions with sodic chloride or magnesic 

 sulphate. On the other hand, it is soluble in distilled 

 water, and has a definite coagulating point, the change 

 taking place at 52'C. This is a much lower temperature 

 than is found necessary to coagulate the animal albumins, 

 which remain unchanged up to about jo to 80C. It can 

 be separated from edestin by dialysis, which throws down 

 the latter, but leaves the leucosin in solution. 



The proteose is perhaps not properly included as a re- 

 serve proteid of the grain. As we shall see changes take 

 place in the wheat kernel in consequence of keeping after 

 maturity, so that this body may be rather one on its 

 way to such a condition as will enable it to be transported 

 from the seed, thus forming a link with the circulating 

 proteids and not a truly reserve product. The proteoses are 

 as a rule the first products of the action of a digestive 

 ferment. 



This body, whatever be its actual position in this 

 respect, can be isolated from wheat flour, freshly ground, 

 and extracted with dilute saline solution. After such an 

 extract has been dialysed till the edestin is all precipitated, 

 and subsequently boiled to remove the leucosin, it still gives 

 proteid reactions. Saturation with sodic chloride, or the 

 addition of about 20 per cent, of the same salt after acidu- 

 lating the solution with a little acetic acid, throws down the 



