H57 
Embryo and Aleurone Layer of Hordeum . 
The point to be considered in these comparative experiments is not so 
much the velocity of liquefaction as the point to which saccharification 
of starch paste may proceed. 
Another series of experiments was then carried out on a larger scale 
as follows. Neither secretions nor extracts were standardized in this case, 
the object being to carry out prolonged digestions and then to determine 
the more important constants of these. 
The following procedure was adopted in this and subsequent series:— 
Two grammes of starch (potato) and 50 c.c. of water were placed in each 
of a series of 100 c.c. flasks, and the starch suspension, gelatinized at 65° C. 
and afterwards cooled to about 55° C., transferred to a thermostat retained 
at the latter temperature. Separate digestions were then carried out with 
embryo and aleurone-layer secretions and aqueous extracts of endosperms 
and inner endosperms at the various temperatures and times given in the 
table which follows. Toluene served as the antiseptic, and the flasks were 
securely corked during and at the termination of each experiment. Amylo- 
lytic action was arrested by plunging the flasks into a boiling water-bath for 
15-20 minutes. The contents of each, after cooling to I5°C., were then 
brought to 100 c.c., filtered, and the different determinations recorded made 
in duplicate on the clear filtrate. 
In each instance the values are adjusted by applying a correction for 
the copper-reducing substances found in the starch and added enzyme- 
containing solution. 
TABLE XXVI. 
Conversion of 4 % Potato Starch with Embryo and Aleurone- 
layer Secretions and Aqueous Extracts of Endosperms 
and Inner Endosperms. 
Exp. 
Source of amylase. 
[«] D. 3-93 
R- 3*93 
Final 3 coloration 
with iodine . 
Temperature of conversi 
55° C. 30° C. 
1. 
Embryo secretion 
I48.2° 
63.29 
No coloration 
(flours) 
(/lours) 
14 
2. 
Aleurone-layer secretion 
145*5° 
64*5 
Faintest violet 
j f 
4 
14 
3. 
Endosperm extract 1 
I49.2 0 
70*0 
No coloration 
14 
4- 
1 
>3 33 
I 49 *8 
70-6 
H 
5- 
2 
99 99 
Inner endosperm extract 
140.0° 
69*5, 
99 
3 
— 
6. 
155*9° 
7.66 
Blue 
8 
14 
The blue coloration (Experiment 6) persisted throughout the whole 
course of this experiment. 
It is to be noted that the colour reaction given by the aleurone-layer 
secretion (Experiment 2) was of the faintest violet. The progress of 
liquefaction in Experiments 3, 4, and 5 was practically at the same rate, as 
judged by inspection of the limpidity and mobility of digestion liquid. 
1 Culture of distal halves of endosperms, 7 days, calcium sulphate. Seeds steeped 48 hours 
in absolute alcohol, 48 hours in water. 
2 Endosperms of air-dried seeds steeped as in 1 . 
8 Colour reactions with iodine recorded in table noted at termination of digestion at 55 0 C. 
