Embryo and Aleurone Layer of Hordeum. 809 
The above example will serve to explain the mode of expression used 
in the tabular statements in the different sections descriptive of experi¬ 
mental work. 
It is further assumed that, at least in the majority of instances, the 
augmentations of amyloclastic enzyme unmasked under the conditions of 
experiment are actually due to an increase in amount of the enzyme itself 
and not to activation of a non-increasing mass of enzyme. That is to 
say, production of enzyme as opposed to augmentation of enzymatic ac¬ 
tivity is implied, although it is conceded that the latter phenomenon may 
in the ordinary course of events obtrude itself, but purely in a subordinate 
measure. 
It is conceivable that during the various progressive phases of culture, 
e. g. of isolated endosperms, the chemical and physical changes in residual 
endospermic substance may at each phase influence its amyloclastic ac¬ 
tivity, some idea of the extent to which this occurs being rendered evident 
by starch digestion experiments. The chief factors comprised here are 
actual augmentation of amylase together with modification of its activity 
by concomitant changes in the reaction medium induced by changes 
in the chemical and physical properties of the material under examination. 
Inactivation of an enzyme can readily be induced, the agent and its 
approximate amount being readily enough determined ; it is otherwise, 
however, when we turn to the question of the activation of an enzyme. The 
view held here is that a given enzyme possesses a finite capacity for 
work which does not exceed certain limits,, and the display of this 
maximal capacity depends upon the provision of optimal working con¬ 
ditions. Wherever apparent activation occurs it is because in the previous 
conditions of experiment a retarding factor or factors were included. 
In dealing with material possessing such variable amyloclastic capa¬ 
cities as structural parts of seed, the adoption of the foregoing method 
of expressing results is permissible. In order to meet the changes in 
magnitude of this capacity modifications in the method of starch diges¬ 
tion are unavoidable. Moreover, for the purpose of rendering the results 
of one series of experiments comparable with those of others, the con¬ 
ditions must be selected in. such manner that the R of the mixed starch 
digestion products does not exceed the limiting value indicated by Kjeldahl’s 
‘ proportionality law and this condition has been strictly adhered to 
throughout the course of this inquiry. 
Experiments such as those briefly outlined afford striking evidence 
of the individuality of the objects which have been subjected to examination, 
and this factor alone probably overshadows those which may intervene 
during starch digestion, conditioned by alteration in number of objects, 
time, and concentration of starch employed. 
The selection of what may appear to be comparatively small numbers 
