Embryo and Aleurone Layer of Hordeum. 803 
endospermic depletion. Fuller reference to this phase of the question may, 
however, be deferred until experimental evidence has been adduced which 
bears on the nature of the amylase existent in the inner endosperm and the 
behaviour of the isolated tissue under the variable experimental conditions 
selected. 
The chief result of their interesting inquiry is to demonstrate that 
under certain conditions of extraction the amylase of the resting seed 
undergoes a tangible increase in quantity. 
That the embryo secretes an active amyloclastic enzyme, the secretory 
function being localized in the scutellar epithelium, has been convincingly 
demonstrated by the investigations of Brown and Morris ( 1 . c.). 
The glandular nature and secretory capacity of the aleurone layer has 
been rendered highly probable by the work of Brown and Escombe (barley) 
and Haberlandt (rye), and suggested by the researches of Linz (maize) and 
Griiss (barley), but opposed by Hansteen and Puriewitsch, who contend that 
its enzyme-secretory or generative capacity is not superior to that possessed 
by the amyliferous cells, in fact that it (the aleurone layer) represents 
physiologically an undifferentiated portion of the reserve system of the seed. 
Throughout, the capacity to secrete or generate amylase possessed by 
the different anatomical parts of the grain (embryo, aleurone layer, endo¬ 
sperm, and inner endosperm) has been investigated as far as possible 
quantitatively . The methods devised and adopted comprised the prepara¬ 
tion of sterile material, the establishment of cultures of isolated parts of the 
seed on nutrient or experimental substrata and their maintenance under 
aseptic conditions, and the subsequent quajititative investigation of both 
objects and media either for amylolytic enzyme or the products or evidence 
of amylolytic activity. 
Sterilization of material. Sterilization of grains was necessarily re¬ 
sorted to to eliminate the possibility of the disturbing influence of micro¬ 
organisms, and because of the inadmissibility of the employment in the 
media of the experiments to be described of antiseptic reagents even in 
minute concentrations. 
Further, in certain instances, notably in the case of experiments with 
inner endosperms, it was necessary to carry out cultural experiments of 
lengthy duration in order to afford these objects full opportunity of display¬ 
ing their presumed powers of auto-depletion. 
Intact air-dried seeds were subjected to a preliminary steeping in either 1 
10 % CuS 0 4 or 2 absolute alcohol for periods of time varying from 24 to 72 
hours. 
1 Latterly, in order to provide for the more efficient aeration of the material, the closely fitting 
stopper was removed and the bottle covered with a sterilized funnel. 
2 Wherever departure from the method described above has been made reference is made to 
the fact in the text. 
