Embryo and Aleurone Layer of Hordeum. 
1191 
TABLE XLIV. 
Amylase Content of Endosperms, Inner Endosperms, and 
Aleurone Layers for Dehusked Steeped Seeds. 
Chilian barley. Seeds steeped successively in (i) absolute alcohol, (2) water; 48 hours in 
each reagent. 0*5 % papain, 20 hours. Antiseptic, nitrobenzene. 
Exp. 
Objects. 
Amylase per 20 objects per hour 
(equivalent to mg. Cu ). 
1. 
2.5 endosperms 
8070 
2. 
2 '5 5 > 
79*5 
3 - 
2-5 inner endosperms 
4888 
4 - 
2*5 
554 s 
5 - 
2*5 aleurone layers 
34*4 
6. 
2-5 
3181 
There is an obvious reduction of amylase in the endosperm (compare 
Table XLI) and inner endosperm (compare Table XLII) and an increase 
in that of the aleurone layer. The reduction of enzyme apparently falls 
more heavily on that of the inner endosperm ; it does not follow, however, 
that some reduction does not occur in that of the aleurone layer, and if this 
be so, then the increase in the enzyme content of this tissue due to papain- 
digestion is actually greater than the value determined. The results 
observed may be conditioned to some extent by the mere separate digestion 
of these tissues (aleurone layer and inner endosperm), but the digestion of 
the endosperm (in which these structural parts are mixed) also shows 
reduction and therefore fails to lend support to this suggestion. A partial 
explanation may be suggested by the application of Ford and Guthrie’s 
hypothesis, namely, the diffusion away, during steeping, of salts or salt-like 
substances and others, some of which, by virtue of their amphoteric properties, 
protect the released amylase, but bodies of the same type are, according to 
this hypothesis, contributed by papain. 
The explanation, however, is more probably associated with the differ¬ 
ences in the biological attributes of the two tissues. 
There is good reason to believe that we are dealing with tissues which 
differ in this important respect. The aleurone layer is distinctly living; the 
inner endosperm, on the contrary, if it possesses vitality at all, can hardly be 
regarded without ample qualification as a living tissue. The inner endo¬ 
sperm, whether it forms an integral part of the seed or whether it is 
isolated, comports itself like a mass of dead tissue; the processes induced 
in it, viz. the augmentation of enzyme and the limited digestion changes, 
under cultural conditions and also by different digestion methods, are auto¬ 
digestive in character and more or less finite in extent. During steeping 
of the seed, water enters freely into the inner endosperm tissue, and 
what happens it is wellnigh impossible to outline. The net result is 
apparently a reduction in its enzyme content as shown by subsequent diges¬ 
tion, but, on the other hand, during steeping of the intact seed the secretory 
