O'Brien . — The Proteids of Wheat . 219 
Tannic acid (cone.), osmic (io°/ o ) and picric (cone.) acids 
dissolve the core, leaving the membrane. 
The Proteids of the Aleur on- Layer . — The colour-reactions 
and staining properties of the membrane of the aleuron-grain 
show its proteid nature. But it is improbable that the large 
amount of nitrogenous matter shown by analysis to occur in 
bran is confined to the peripheral parts of the aleuron-grains 
and the protoplasmic network. A partially proteid com- 
position of the core of the aleuron-grain has been suggested 
by its solubility, as already mentioned ; it is further supported 
by the composition and behaviour of an extract made from 
bran by water — it being remembered that water dissolves the 
core and not the membrane, and that it leaves the greater part, 
if not the whole, of the cytoplasm untouched. 
The watery extract of bran seems to contain two proteids, 
giving Millon’s, Piotrowski’s, and the xanthoproteic reactions : 
(1) a coagulable proteid, probably a globulin dissolved in 
presence of the mineral salts ; (2) a proteose which may be 
precipitated by concentrated salt-solutions from the filtrate 
from (1) after its coagulation by heat. Evaporated to dryness, 
the extract yields a gelatinous substance, yellow in bulk, and 
semi-transparent, separating out in part in small round spheres. 
These spheres are interesting as being, I believe, artificial 
aleuron-grains ; they give all the reactions of those embedded 
in the cell-protoplasm. It may be specially noted that their 
outer layer partially resembles the membrane of the natural 
aleuron-grains, dissolving in water and even in potash only 
after some hours’ treatment. 
Bran extracted with alcohol ( 5 °°/ 0 ) yields a solution con- 
taining proteid, which agrees in its reactions with the extract 
made from flour. 
Examination of the flakes of bran after treatment with 
water shows the core of the grains to have dissolved ; but the 
process is slow in unbroken cells, and the small amount of 
matter in solution obtained from bran by short treatment with 
water depends on the difficulty with which this penetrates to 
the grains. This has also been proved by Jago’s results, the 
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