Embryo and A leurone Layer of Hordeum. 811 
from, but also how closely the amyloclastic secretory powers of the objects 
parallel each other; an approximation of sufficient nearness for ordinary 
biological investigation. 
III. Amyloclastic Secretory Capacity of the Embryo of Barley. 
The salient features of the general anatomy and histology of the barley 
embryo have been so frequently described that this portion of the subject 
calls for limited reference only. 
The organ of special interest, the scutellum, is a shield-shaped expansion 
which over its greater area is in close apposition, but not organically united 
to the proximal end of the inner endosperm, the limiting layer forming the 
boundary between the scutellum and endosperm consisting of a single layer 
of columnar cells. 
The functions of the scutellum are twofold—absorptive and secretory. 
It is regarded from the standpoint of morphological botany as a cotyle¬ 
donary organ, and from the physiological standpoint as a glandular tissue, 
the secretory function being localized, at least principally, in the columnar 
or epidermal layer ; the enzymes arising as a result of activity of secretory 
mechanism, amylase, cytase, and probably others being largely destined for 
extra-cellular work. 
While it is broadly accepted that the scutellum possesses and exercises 
both absorptive and secretory functions it is perhaps not so generally 
recognized how important is the former function in the regulation of the 
complex processes which have their seat of action in the inner endosperm 
during the progress of normal germination, not only in regard to the removal 
of simplified products of enzymatic action, but to the accumulation of enzymes 
and the continuance of their specific activity. 
It has been, and still is, a question of controversy whether the various 
degradation changes of the complex storage substances in inner endosperms 
can be or are induced solely by the action of enzymes which are elaborated 
by the embryo, or by enzymes which arise in or are generated by the inner 
endosperm independently of the embryo. 
Demonstration of the possession by the embryo of a distinct amylo¬ 
clastic secretory function and its localization in the columnar or secretory 
epithelium is due to Brown and Morris ( 1 . c.), but this particular aspect 
of the subject, as far as can be ascertained, does not appear to have been 
the object of any subsequent independent reinvestigation. 
The secretory function ascribed to the embryos by Brown and Morris, 
although generally accepted, has been more recently challenged by Ling. 1 
The investigation of the amylolytic secretory power of the embryo 
in this inquiry embraces two lines of attack : (i) cytological, (2) biochemical, 
Journ. Inst. Brewing, xv, p. 651. 
