H75 
Embryo and A leurone Layer of Hordeum. 
far as the writer is aware, been demonstrated in the case of Hordeum 
(barley). The fact that the aleurone layer possesses similar physiological 
attributes to those of the columnar epithelium suggests that the endosperm 
of Hordeum may possibly represent an abortive or undifferentiated embryo, 
in which case the aleurone layer may on the evidence adduced be regarded 
as the analogue of the columnar epithelium. 
XI. Influence of the Embryo on the Augmentation of 
Amylase by the Inner Endosperm. 
There can be little doubt that, apart from its secretory functions, th e 
embryo by the exercise of its absorptive function modifies the rate of 
augmentation of amylase in the inner endosperm. Removal of the products 
of amyloclastic activity is a primary essential if the gradual transformation 
of the starch reserves is to proceed without interruption. If, for example, 
the accumulation of starch transformation products exceeds certain limits, 
then there the progress of endospermic depletion may be markedly retarded. 
It appeared to be of interest to study the possible influence the embryo 
may exercise on the capacity the inner endosperm possesses of augmenting 
its amylase content. With this object in view sterilized steeped seeds were 
completely divested of their aleurone layers, and plate cultures were then 
prepared of inner endosperms with their embryos attached. The objects 
were embedded in 5 % gelatine-M.S. medium, and the cultures thus estab¬ 
lished continued for periods of four and six days. Media and objects were 
then separately investigated for amylase by the methods already described. 
The results of these experiments are summarized in the following 
table:— 
TABLE XXXIV. 
Cultures of Inner Endosperms with their Embryos 
ATTACHED. 
P . Culture Amylase per 20 objects per hour in :— 
period. Medium. Inner endosperms. Scutella. 
1. 5 embryos with inner endosperms attached 4 days 3174 952 75 
2. 5 embryos with inner endosperms attached 6 days 3055 873 105 
The results are of interest in showing that the augmentation of enzyme 
in the inner endoserm proceeds more rapidly under these conditions than in 
the isolated inner endosperm under similar conditions of cultivation. 
The relatively larger total amounts of enzyme, however, are partly 
to be accounted for by the secretory activity of the embryo, and probably 
also by the more prompt removal of the products of amyloclastic activity, 
leading to the more rapid release of the residual £ latent * amylase of the 
inner endosperm. 
The embryo in these circumstances probably secretes more actively 
than under the artificial conditions described in an earlier section of this 
