58 
PHARMACEUTICAL BOTANY 
Gliadins are nearly or wholly insoluble in water but soluble in 
70 to 90 per cent, alcohol. 
Nucleins are insoluble in water but soluble in alkaline solutions. 
The following tests are of value in determining the presence of 
proteins. 
Lugol’s solution stains proteins yellow or brown. 
Concentrated nitric acid stains proteins yellow. This color 
becomes deeper upon the addition of ammonia water. 
Million’s reagent stains proteins a brick-red. 
Concentrated solution of nickel sulphate colors proteins yellow 
or blue. 
If sections are placed for an hour or two in a solution of 1 Gm. of 
sodium phospho-molybdate in 90 Gm. of distilled water and 5 
Gm. of nitric acid, the proteid substances appear as yellowish 
granules. 
The globulins (phytoglobulins) frequently occur in bodies called 
“aleurone grains.” 
ALEURONE GRAINS 
Aleurone grains are small bodies found in seeds particularly those 
containing oil, and like starch grains often are characteristic of the 
genus or species. Each aleurone grain consists of a ground sub- 
stance (composed of amorphous proteid matter soluble in water, 
dilute alkali or acid), in which are usually embedded one or more 
phyto-globulins (insoluble in cold water, but soluble in less than 1 per 
cent, solution of an alkali, in dilute HCland acetic acid), one or more 
transparent globular globoids composed of Ca and Mg phosphate 
(insoluble in water and dilute potash solution but soluble in 1 per 
cent, acetic acid solution), and frequently a crystal of calcium 
oxalate, the whole being enclosed by a protoplasmic membrane (soluble 
in water). 
The proteins insoluble in the cell-sap water are made soluble for 
translocation by means of proteolytic enzymes which change them 
into proteoses and peptones. 
17. Mucilages and gums are those substances occurring in plants 
which are soluble in water or swell in it, and which are precipitated 
by alcohol. 
