Embryo and Aleurone Layer of Hordeum. 823 
In short, the action of these agents on the embryo is signalized by the 
complete and rapid arrest of its secretory functions, minimal amounts only 
of enzyme being pre-existent in its scutellar tissues, and consequently only 
minimal amounts of enzyme are found in the culture medium. On the 
other hand, the inhibitory and fatal action of the same agents on the aleurone 
layer is marked by comparative slowness, the secretory function being more 
tardily impaired. Although considerable amounts of amylase are thus 
accumulated by the anaesthetized aleurone layer, its augmentative capacity, 
as compared with similar objects not subjected to the injluence of such agents, 
suffers marked reduction. 
This reduction of amyloclastic enzyme, as the result of the interference 
with and arrest of the secretory mechanism of a living tissue, is the kind of 
behaviour we should anticipate in the case of the aleurone layer. Com¬ 
plete and prompt arrest of its secretory powers (as in the case of the embryo 
as observed by Brown and Morris) could not occur ; the apparent secretion 
of enzyme by the aleurone layer under complete anaesthesia, described 
in this section, really represents for the most part the passive diffusion 
of the accumulation of pre-existent enzyme 1 in its cells—a fact to be 
elicited only by the employment of quantitative methods of inquiry. 
The augmentative capacity of the aleurone layer under anaesthetic 
conditions of culture suffers marked reduction, and this is taken to signify 
that the aleurone layer is a living tissue—a fact fully supported by other 
considerations. 
Had its augmentative capacity been equal to or greater than that 
exhibited by similar aleurone layer fragments cultivated on similar media 
without the addition of antiseptics recognized as agents fatal to living 
protoplasm, the claim that this tissue possesses vitality would be rendered 
extremely difficult to maintain. The inner endosperm, as we shall see 
(Section IV A, pp. 824-37), does actually exercise its augmentative capacity 
as rapidly and to the same extent in the presence or absence of antiseptics. 
The argument may be advanced that the method of treatment to which 
the isolated aleurone layers were subjected does not preclude the possibility 
of loss of amylase by the enzyme diffusing from the fragments of tissue into 
the steeping medium. The fact remains, however, that neither the aleurone 
layer nor the embryo after such preliminary treatment any longer possesses 
the power of exercising its secretory powers to the same extent as non- 
anaesthetized objects. 
The following experiments will serve to show that in the foregoing 
experiments with anaesthetized aleurone layers (Tables IX and X) the 
1 The chloroformed embryos examined by Brown and Morris were probably taken from seeds 
immediately after steeping ; at this stage they would contain little or no amylase. If taken at later 
stages from germinating seeds, the accumulated amylase would probably diffuse out and action upon 
barley starch would have been demonstrable, and unless quantitative examination were resorted to 
confusion similar to that instanced in the case of the aleurone layer would have arisen. 
