1196 Stoward.—A myloclastic Secretory Capacities of the 
amount of enzyme in the inner endosperm of the germinated seed is taken 
as the sum of that furnished by this tissue, plus that derived from the 
embryo and aleurone layer. The values given in the final column (3) are 
the differences obtained by subtracting the values of column (1) from 
column (2). The amounts of amylase contributed by the aleurone layer 
and embryo calculated on this basis are by no means insignificant, for they 
amount to roughly 45-55 % of the amylase present in the inner endosperm 
taken at the periods of germination indicated. 
The assumption has been tacitly made, however, that the amylase of 
the inner endosperm and that derived from the aleurone layer and embryo 
are identical in their nature and amyloclastic attributes, and it has been 
further assumed that the amylase which originates in the inner endosperm 
undergoes no reduction in amount as the result of its activity. This cannot, 
however, be regarded as correct in the light of the experimental evidence 
afforded by the study of the action in situ of the enzyme, which is pre¬ 
existent and accumulates in the inner endosperm, or of their behaviour 
towards gelatinized starch. In short, the inner endosperm appears to 
be an exchequer which receives enzymatic contributions from the active 
secretory tissues, and also possesses the power of augmenting its enzyme 
content autonomously. But the currency it receives is of more value, espe¬ 
cially as far as its internal transactions are concerned, than that which it 
originates itself, and for this reason estimations of the amount of amylase 
a tissue (such as the inner endosperm) is capable of augmenting are of 
subordinate significance in relation to the question of endospermic de¬ 
pletion, unless it can be definitely shown that the enzyme possesses a 
capacity of attacking the starch reserves placed at its disposal, equal or 
superior to that possessed by the ‘ secretion ’ variety elaborated by the 
embryo and aleurone layer. 
The estimates given of the contributory share derived from the aleurone 
layer and embryo are by no means over-estimated, for there is evidence to 
show that the amylase of the inner endosperm, when it does manifest its 
comparatively feeble powers of attack on endospermic starch grains, 
probably undergoes either inactivation or destruction. And if this 
phenomenon also takes place in the inner endosperm during the march of 
the germinative processes, then the amounts of enzyme contributed by the 
veritable secretory tissues (the scutellar epithelium and aleurone layer) are 
probably greater than those given in the above table ; in other words, the 
values given tend to under- rather than over-estimate the amount of amylase 
from these sources. 
