Embryo and Aleurone Layer of Hordeum. 1159 
a definite chemical individual, in the latter a body about which we know 
comparatively little either as regards its constitution or properties. 
The object of the foregoing experiments has been to show that wher¬ 
ever the influence of the aleurone layer has been operative there is produced 
an enzyme which possesses properties which in all respects are comparable, 
if not identical with those of the enzyme secreted by the columnar epithelium. 
The introduction of Experiment 6 in the series had for its object the 
demonstration of the fact that wherever the functions of the aleurone layer 
have been eliminated or rendered inoperative the enzyme present does not 
possess either the attributes of that of the embryo or aleurone-layer 
secretion. 
The means of differentiation between the enzymes from these different 
sources hitherto relied upon were confined to observations (1) on the mode 
of attack on intact starch grains, (2) on the quantitative demonstration 
of the superior depletive activity possessed by the enzymes secreted by the 
embryo and aleurone layer, and now they are still further emphasized 
by direct experimental evidence afforded by starch-paste conversions. 
The following experiments were carried out with inner endosperms 
which had been placed on calcium sulphate substrata for ten days. A 
digestion with soluble starch by the ‘ direct ’ method of digestion showed 
that the amount of ‘ free * amylase present was minimal, and it was there¬ 
fore of interest to ascertain whether by the predigestion procedure with 
papain or neutral salt the ‘ latent ’ enzyme liberated by these methods 
would acquire any of the properties (as judged by their action on starch 
paste) of the more powerful amyloclastic enzymes derived from the embryo 
and aleurone layer. 
TABLE XXVII. 
Starch Conversions with Inner Endosperms. 4 % Starch 
1. 10 inner endosperms pre» 
digested 40 hrs. with 25 
c.c. o*5 % papain at 30°C. 
2. 10 inner endosperms pre¬ 
digested 40 hrs. with 25 
c.c. 0*5 % papain at 30° C. 
3. 10 inner endosperms pre- 
digested with 5 % KC 1 . 
40 hours at 30°C. 
4. 10 inner endosperms extract¬ 
ed 4 hours with 25 c.c. 
water at 3o°C. 
5. 10 inner endosperms finely 
ground and added directly 
to starch paste. 
Paste. 50 c.c. 
^• 3*93 
10 c.c. filtered extract 
i -47 
10 c.c. filtered extract, 
faintly acidified with 
dilute acetic acid 
i -47 
10 c.c. filtered extract 
1.70 
1-85 
J* 
2.69 
Temp, and Time . 
[a]Z>. 3.93 55 0 C. 30 °C. 
166° 12 hrs. 27 hrs. 
173 - 2 ° „ 
94 - 77 ° 1 ft 
n >} 
1 79 ’ 7 ° >> >> 
Values not adjusted for influence of neutral salt. 
