Embryo and Aleurone Layer of Hordeum . 
1199 
TABLE L. 
Amylase Content of Mixed Root, Stem, and Leaf- 
Structures of Tropaeolum. 
Digestion method . 
Papain, 0.5 % 
Auto-digestion 
Direct digestion 
Papain 0.5 % 
Direct digestion 
Antiseptic. 
Chloroform 
Amylase per grm. of tissue per 20 hours 
(equivalent to mg. of Cu). 
529 
628 
712 
Amylase content of Tropaeolum stems. 
(a) (A) 
Chloroform 501 448 
„ 8l 7 975 
The primary deduction to be drawn from these results is that the 
condition of existence of the amylase, especially in the leaf-tissue of 
Tropaeolum , which we may justifiably assume is the ‘translocation* 
variety, and that in the reserve system of the barley grain are materially 
different. Papain-digestion of the tissues of Tropaeolum , unlike papain- 
digestion of the inner endosperm of the air-dried or steeped seed of 
barley, does not lead to an increase but to a decrease of amylase, and 
if we assume that the special function of papain is to release the ‘ latent * 
amylase existent in a tissue, then it appears to be permissible to conclude 
that in actively metabolizing tissues, such as those of Tropaeolum , the 
amylase present exists entirely in the ‘ free ’ condition, the term ‘ free ’ 
implying that practically the bulk of the enzyme present is unmasked 
by direct digestion, and that papain-digestion of such a tissue fails to 
afford higher results than those furnished by direct digestion. 
The term ‘ latent ’ enzyme, as employed by Ford and Guthrie, im¬ 
plies that a certain proportion of the enzyme existent in the mature 
inner endosperm cells of barley presumably becomes associated with a 
protein complex from which apparently it must be dissociated before it 
can manifest its active powers. 
During the course of the present investigation, other points of view 
have presented themselves regarding the nature of the ‘ latent ’ enzyme 
of the inner endosperm. The chief function of the amylase existent in 
the endosperm of barley during the development and maturation of the 
grain relates to the translocation of starch from one cell of the endo¬ 
sperm to another. When the grain reaches maturity the enzymes and 
reserves are immobilized, and a considerable proportion of the amylase 
then probably undergoes a series of changes of which ‘ latent ’ amylase 
represents only a phase. 
It seems probable, judging from the comparatively feeble capacity 
the amylase of the inner endosperm has of attacking any other than the 
small immature starch grains, the feeble auto-depletive powers of the 
