222 
O’Brien . — The Proteids of Wheat. 
is soluble in i°/ o potash. They, therefore, nearly resemble 
ordinary aleuron-grains ; but the enclosure being soluble in 
dilute potash, and in salt-solution on standing, is not a true 
globoid, but resembles the core of the aleuron-grain of Wheat. 
Barley is exceptional in having an aleuron-layer several 
cells in thickness. The aleuron-grains resemble those of 
Wheat in form and behaviour ; but the membrane is more 
soluble in potash, and the core less sharply defined. 
Rye . — The aleuron-grains show considerable variation in 
size, and resemble those of Zea in the large proportion of 
proteid present. Haberlandt 11 mentions the occurrence of as 
many as four globoids. 
From the preceding observations it would appear that 
the aleuron-grains of the Gramineae do not present that 
degree of differentiation in which the mineral matters are 
sharply separated off, as a globoid, from the proteid con- 
stituents of the grain. Only the membrane, consisting 
usually of coagulated or at least of very insoluble proteid, 
is here differentiated. Within this, the substance of the 
aleuron-grain contains, as has been proved by Mr. Groom, 
the phosphates of magnesium and calcium, like the globoids 
of typical aleuron-grains. But that it likewise consists of 
some nitrogenous substance seems the conclusion separately 
drawn by Johanssen and Liidtke from their different obser- 
vations, and the present results confirm this view. Hence it 
seems to me that the aleuron-grains of Wheat, within a mem- 
brane of coagulated proteid, contain a sphere of a homogeneous 
substance combining the proteid (globulin and proteose) and 
mineral matters, differentiated in other plants into ground- 
substance and globoid. Thus the various apparently conflict- 
ing theories as to the aleuron-grains of the Gramineae may be 
harmonised. 
Finally, I wish to express my indebtedness to Professor 
Vines for the suggestions he has made, and my thanks for the 
kind interest he has taken in my work. 
Botanical Laboratory, Oxford, 
March , 1895 . 
