MICRO-CHEMISTRY OF THE CELL. 35 



i. Give the reactions characteristic of proteids. 

 ii. Soluble, usually, in potash. 



The reactions of these bodies are very different in different 

 seeds ; the following will serve as types : 



1. Grains without crystalloids. 



(a). Soluble in water : peony, almond, cherry, apple. 

 (6). Partially soluble in water ; more or less readily soluble 

 in 10 per cent, solution of common salt. 



a. Soluble in saturated solution of common salt : lupine, 



pea, bean, scarlet runner. 



j8. Soluble in saturated solution of common salt only after 

 treatment with alcohol : sunflower, turnip, cress, 



2. Grains containing crystalloids. 



(a). Partially soluble in water ; more or less readily soluble in 

 10 per cent, solution of common salt. 



a. Soluble in saturated solution of common salt : Brazil 



nut, pumpkin. 

 . Soluble in saturated solution of common salt only after 



treatment with alcohol : castor-oil plant, walnut. 

 In all cases a mass (globoid) of mineral matter remains behind 

 after the solution of the grain ; this is soluble in acetic acid. The 

 sections should be examined in alcohol. 



h. Tannin : gives the cells in which it is present a 

 brownish colour. 



i. Coloured deep brown by potassium bichromate, or 

 chromic acid. 



ii. Coloured greenish-blue by dilute solution of iron 

 sulphate. 



iii. On treatment with a solution of ammonium 

 molybdate in a strong solution of ammonium chloride, 

 either a voluminous yellow precipitate is formed (showing 

 presence of tannin), or a red colour is produced (show- 

 ing presence of tannic, i.e., digallic acid). 



i. Resin : occurs in drops in the cells bounding 

 resin-passages as well as in the passages themselves. 



D 2 



