Embryo and Aleurone Layer of Hordeuni . 801 
a given tissue is no longer regarded as of value for the determination of the 
possession or non-possession of vitality by that tissue. 
The unqualified statement that the endosperm (barley) is auto-depletive 
is supported by experimental demonstration of the phenomenon, but the 
conclusion that the demonstration of an auto-digestive capacity for the 
endosperm necessarily proves the claim that the inner endosperm is capable 
of inducing the complete self-depletion of its storage reserves independently 
of the aleurone layer is (as will be shown) probably inadmissible. Again, 
demonstration of the capacity of a tissue to augment its enzyme-content 
(such a capacity the inner endosperm possesses) can hardly be claimed 
to afford adequate evidence of the possession of a capacity for auto-digestion 
unless it be shown that digestive changes in the storage materials of 
sufficient magnitude either accompany or immediately succeed this aug¬ 
mentative capacity. 
Apart from the work of Brown and Morris (embryo of barley) the 
methods of determining relative capacities of isolated endosperm and 
inner endosperm have been either qualitative or of such kind as to afford 
little or no means of evaluating the relative capacities for doing enzyme- 
work possessed by the different anatomical parts of the endosperm. 
The study of the phenomenon of endospermic depletion as investigated 
by the method of experiment of Hansteen and Puriewitsch fails to indicate 
in what relative degree the aleurone layer and inner endosperm participate 
in or are contributory to the processes involved and take insufficient cogni¬ 
zance of possible differences in the properties and potentialities of the 
amyloclastic enzymes which originate in these tissues. 
In particular the methods employed by Linz and Griiss in experiments 
with intact isolated endosperms of maize (although separate estimations of 
the amylase content of the aleurone layer were made at the termination of 
the germination experiment) are open to the objection that they fail to take 
account of the amount of enzyme secreted by the aleuronic tissue during the 
period of cultivation. They amount really to demonstrations of the capacity 
this or that structural part of the seed possesses of augmenting its amylase- 
content. 
Similarly Griiss’s demonstration of the presence of copper-reducing 
substances in thin sections taken from isolated endosperms under germina¬ 
tion conditions, in the absence of the removal of the aleurone layer, fails to 
show that the apparent hydrolysis of starch implied by these experiments 
was due solely to an amyloclastic enzyme generated in situ. 
Material. Two barleys have served as experimental material through¬ 
out the course of investigation, the one a North African and the other 
a brewing Chilian. 
Both were mixtures of H. vulgare and H. liexastichum of the year, 
possessing the customary characteristics of barleys from these sources 
