8o8 Steward.—Amyloclastic Secretory Capacities of the 
to a definite number of organisms (embryos) or structural parts (aleurone 
layers, endosperms, inner endosperms) of the seed. The system adopted 
appeared to be preferable to that of referring it to definite weights of 
the various objects. If weight of material is taken as the basis of reference, 
several well-founded objections present themselves. Determination of 
definite weights of material necessitates desiccation under fixed conditions 
of time and temperature, and even if these be well below that calculated to 
be dangerous to the activity of the enzyme present, it does not follow that 
the enzyme may not undergo, as the result of influence of heat, inactivation 
or actual destruction. Moreover, the possibility of the desiccation of 
material of such different origin and constitution in such a manner as to 
render the weights comparable is excluded by the fact that loss of moisture 
(if the loss is wholly to be attributed to this) by such diverse material is by 
no means uniform, and consequently the residual weights of the various 
structural parts are more or less inadmissible as a basis for calculating their 
enzymatic capacities. 
Were such comparisons confined to objects of the same kind, as, 
for example, isolated endosperms under cultural conditions to be described, 
the objection still would remain. The individuality possessed by the 
objects, the varying degree to which digestive changes progress, leading 
at every stage to variable proportions of unchanged and partly changed 
starch, the outward diffusion of products of change, all conspire to render 
the expression of result on any other than the numerical basis alluded to 
inadmissible and impracticable. 
The manner of expressing results may perhaps be rendered clearer 
by taking an illustrative examplea plate culture consisting of ten 
aleurone layers is established, continued for several days and finally termi¬ 
nated by removal of the cultural objects. Objects and medium are sepa¬ 
rately digested with soluble starch solution for a period of half an hour and 
the amount of reducing sugars determined and corrected in the manner 
described. In the experimental and control digestions five objects each are 
used ; in the similarly conducted digestions with the diluted culture medium 
one half (io c.c.) serves for the experimental, the other half (10 c.c.) for the 
control starch digestion, each half-volume of the total diluted culture 
medium obviously containing an amount of amylase derived from one-half 
(five objects) the total number of objects on the plate. 
Let us suppose that the copper reduction values of the objects and 
medium after applying the control corrections are x and y milligrammes of 
copper respectively, then we shall have - 
Amylase per 20 objects per hour 
in objects equivalent to (x x x \ x 2) = 4 x milligrammes Cu. 
Amylase per 20 objects per hour 
in culture medium equivalent to (y x x -J x 2) = 4y milligrammes Cu. 
