1158 Stoward,—A my toe las tic Secretory Capacities of the > 
There is a rough general agreement in constants for Experiments 1-5, 
indicating that the stage to which conversion had finally advanced in each 
instance was practically of the same order. In particular the colour reactions 
in these experiments with iodine were identical. 
On the contrary the results given by the inner endosperm extract 
(Experiment 6) notably differentiate the general character of the con¬ 
version in this case; not only are the constants of a different order of 
magnitude, but the reaction with iodine throughout the entire period 
of experiment was persistently blue . 
The enzyme present was that of the inner endosperm—the residual 
amyloclastic enzyme of the ungerminated grain of Brown and Morris— 
together with a certain proportion of an enzyme of the same type resulting 
from the liberation of enzyme existent in this tissue which Ford and 
Guthrie refer to as c latent ’ amylase. 
It is to be understood that the author does not consider the ‘ blue * 
coloration stage as final in this experiment; the probable reason why the 
ultimate ‘ violet ’ stage was not attained must be ascribed to the relative 
proportions of aqueous inner-endosperm extract and starch paste employed. 
Invariably in these culture experiments with inner endosperms on 
calcium sulphate, whether established with objects prepared from steeped 
intact seeds (the objection to which is the possible diffusion of enzyme from 
the embryo and aleurone layer, which we have seen may be regarded as of 
small moment when steeping operation is confined to time and temperature 
limits recorded in this paper) or whether inner endosperms are prepared 
from air-dried material and are then steeped, there is a continual draining 
away of the amylase pre-existent initially in the tissue and of the amylase 
which results from the liberation of ‘ occluded * or ‘ latent ’ enzyme, the net 
result of which is that as the culture experiment under these conditions is 
sufficiently prolonged this tissue eventually becomes denuded of its amylo- 
lytic enzyme content. 
The calcium sulphate stratum undoubtedly contains this enzyme during 
the progress and at the termination of the experiment, but the difficulty of 
estimating its amount lies in the fact that experimental difficulties are met 
with ; the distribution of enzymes in the semi-solid medium is not uniform, 
and hence equal division of the substratum by mechanical division into two 
identical halves is impracticable. Similarly in the extraction of the sub¬ 
stratum with water it is impossible to eliminate completely the possible 
adsorption of enzyme by solid CaS 0 4 . Finally, as already insisted, a far 
more accurate estimate of the relative depletive power of an amylolytic 
enzyme contained in or generated by a given tissue is gained by determining 
the amounts of reducing sugars in the substratum than by comparing its 
relative amylase content. 
In the former we measure the amount of a substance which is 
