212 
O'Brien. — The Proteids of Wheat. 
as the aleuron-grains of the Gramineae. Thus he describes 
the grains as small and apparently without enclosures, but 
goes on to say that one can hardly speak of them as aleuron- 
grains, the albuminous material simply drying to a granular 
mass between the starch-grains. Whilst recognising that the 
one or two outer layers of the endosperm in Grasses are free 
from the starch, he does not localise in them the grains 
described. 
In the same year, however, Schenk, finding the not un- 
natural error of considering the aleuron-layer ( Kleberzellen ) 
as the seat of gluten ( Kleber , used in the narrower sense) 
fairly widespread, clearly pointed out that the aleuron-cells 
do not contain gluten. The large amount of nitrogen to be 
found in bran seemed to confirm the popular view ; but 
Schenk showed that this large percentage of nitrogen is due 
(1) to the presence of a nitrogenous substance not proteid in 
nature ; (2) to the adherent parts of the endosperm, its outer 
layers, which are the parts richest in gluten. He first de- 
scribed in detail the reactions of the aleuron-layer. Millon’s 
reagent, he found, did not affect the aleuron-cells ; iodine 
stained them deeply, but as it also stained the testa and 
pericarp he did not consider this as any proof of the presence 
of proteid. Digestion with dilute hydrochloric acid, with 
alcohol, ether, or even with potash, he found to be without 
effect on the cells or their contents ; whilst concentrated 
sulphuric acid gave a blackish colour. Hence he considered 
himself justified in supporting previous writers who had 
insisted on the low nutritive value of the nitrogen of bran. 
The difference between his negative results and those to be 
mentioned later as to the solubility of the contents of the 
aleuron-cells, is probably due to the comparative impervious- 
ness of these cells when intact, the uninjured contents having 
probably never been reached by the reagent. 
For some time no important addition was made to the 
knowledge of aleuron-grains. About 1878, however, the 
aleuron-grains of many groups were described by Professor 
Vines 7 , and their chemical nature investigated ; but no 
