MORPHOLOGY OF THE BARLEY GRAIN". 
13 
and, later, Pfeffer 1 in his review of Hansteen's work. The work of 
Hansteen is of some significance. He found that when the products 
of conversion were constantly removed, the endosperm was able to 
digest itself. His conclusion, however, that the endosperm is entirely 
capable of self-digestion is rather too sweeping, especially since he 
himself found a very active secretion of diastase in the scutellum, the 
existence of which function is hard to understand if it be superfluous. 
It is much more probable that the method used by Hansteen merely 
exaggerated the normal action of such diastase as would naturally 
be expected to be present in the endosperm of the ripened grain, 
for a certain minute amount of diastase is necessarily present in the 
cells of the endosperm to cany on the process of starch infiltration. 
This is, however, merely that phase of diastase needed for the trans- 
location of the starch while the barley gram is forming. Indeed, 
according to the figures of Brenchley, the amount of diastase in the 
growing grain decreases as the grain approaches maturity. It is 
oven reasonable to expect that not only would traces of this enzym 
remain potentially functional in the endosperm of the ripened seed, 
but that the cells of this endosperm, once able to produce this fer- 
ment, would retain such ability to some degree, even in their less 
active condition. The effect of such small quantities of local diastase 
is not, however, to be confused with the vigorous attack that actually 
takes place in the process of germination. The conclusions of the 
writers are supported by those of many investigators, as above cited. 
The theory that the aleurone layer is active in endosperm reduc- 
tion has more in its favor than has that of the self -digest ion of the 
endosperm. The aleurone layer is obviously high in vital energy. 
Its cells have the unmistakable aspect of active protoplasm. Their 
nuclei are large and present a sharp contrast to the distorted plasmic 
centers of the endosperm cells. The aspect of this layer during 
germination also lends much to the support of the hypothesis of its 
being functional. As previously noted, it is not digested with the 
endosperm, but persists until the endosperm is almost entirely ab- 
sorbed. When germination is carried only to that point where the 
purposes of malting have been attained, the aleurone layer is still 
intact. As shown in figure 3, almost perfect sections of this tissue 
may be obtained from ordinary dried brewers' grains, in which the 
entire starch endosperm has been destroyed. In still further support 
of the idea, the disintegration in a newly germinating seed proceeds 
most rapidly directly adjacent to the aleurone layer. At certain 
stages this diastatic movement may be seen to have progressed 
until the thickest part of the endosperm is in a way surrounded with 
digested starch cells. 
1 rfeffer, Wilhelm. Untersuchungen von Herrn Barthold Hansteen im botanischen Institut ausge- 
fuhrten, iiber die Ursachen der Entleerung der R eservestoffe aus Samen. Berichte, Koniglich .^'achische 
Gesellschaft der AVissenschaften, Leipzig Mathematisch-physische Classe. Bd. 45, p. 421-428, 1893. 
