H95 
Embryo and Aleurone Layer of Hordeum . 
attempt to evaluate the amounts of amylase which are contributed by the 
embryo and aleurone layer during the phases of germination cited in the 
preceding tables. 
The inner endosperm during the progress of germination is regarded 
as the recipient of amyloclastic enzymes which arise as secretions of the 
embryo (scutellar epithelium) and aleurone layer, both of which tissues 
have been shown by direct experimental evidence to be glandular in function. 
The inner endosperm possesses the capacity of augmenting its amylase 
content. The tissue is probably non-living, and is unable to deplete itself. 
This phenomenon occurs indubitably when the aleurone layer forms an 
integral part of the endosperm, but does not when the vital activity of the 
aleurone layer is annulled, and these supplementary facts are regarded as 
supporting the assertion that the aleurone layer is living and secretes the 
enzyme which principally conditions depletive change. Other experi¬ 
mental evidence points to the same conclusion. The assumption, therefore, 
that part of the amylase found in the inner endosperm is secreted and 
excreted by the aleurone layer receives justification, and similarly it can 
be demonstrated that the embryo also contributes a share. 
If we assume that the papain-digestion value for the inner endosperm, 
after removal from the steeped seed, furnishes the limiting value of its 
amyloclastic capacity, and further assume that it represents its finite 
augmentative capacity (an assumption justified by the evidence adduced 
for regarding it as not representing a living tissue), then we can calculate 
approximately, from the increase of amylase which takes place in this tissue 
during certain phases of the germinative process, the relative amounts of 
amylase derived from the combined secretory activities of the embryo and 
aleurone layer. These are shown in the following table :— 
TABLE XLVIII. 
Relative Amounts and Sources of Origin of Amylases 
present in Inner Endosperms of Germinated Seed. 
Papain-digestion. 
Amylase initially present in 
inner endosperm from steeped 
seed. 
Amylase present in inner 
endosperm after days of 
germination. 
Amylase derived from embryo 
and aleurone layer. 
Amylase per 20 objects {equivalent to mg. Cu ). 
(1) 
5000 
55 °° 
(2) 
4 days 8900 
7 days 9800 
( 3 ) 
4900 
4300 
The values given under columns (1) and (3) represent the amounts of 
enzyme, as determined by papain-digestion, present in the inner endosperm 
initially, and after four and seven days’ germination respectively. The 
