1161 
Embryo atid Aleurone Layer of Hordeum . 
under identical conditions by removing two drops of the digestion mixture, 
diluting it by the addition of 5 c.c. of distilled water, and then adding 
two drops of iodine solution. These results definitely show that the 
amylase of ungerminated barley, even after predigestion with papain and 
subsequent lengthy digestion with starch paste, is incapable of advancing 
the conversion beyond that stage which gives a violet coloration with 
iodine. That is to say, the experiments so far considered afford presump¬ 
tive evidence of the fact that the amylase of ungerminated grain does not 
undergo transformation into or acquire one of the most specific properties 
ascribed to the amylase found in the malted corn, viz. action on starch 
paste to the no coloration phase with iodine. 
After arrest of amylolytic action by boiling, cooling, and diluting to 
100 c.c. and then filtering, the determinations made on the clear filtrate 
yielded the following constants: R. 3-93, 58-29; [a] D. 3-93, 137-2°— 
values which no doubt arise as result of series of direct and reversionary 
actions. 
The experimental evidence so far adduced shows that the amylase 
demonstrable in inner endosperms cultivated on calcium sulphate is 
differentiated from that contributed by the embryo and aleurone layer by 
the inferiority of its capacity to attack barley starch in the condition in 
which it exists in the amyliferous cells, by its mode of attack on starch 
grains, and further by its incapacity to carry the conversion of starch paste 
beyond the violet coloration phase, as well as by its inferior starch- 
liquefying power. 
It remains to add that the relatively large share attributed to the 
residual amylase in the digestion of the starch reserves of the inner endo¬ 
sperm during germination of the grain, as suggested in the more recent 
contributions to the subject, has been chiefly due to a tendency to confuse 
enzyme augmentation with enzyme activity and to regard the former 
phenomenon as an index of the latter. It has been frequently shown in 
the present inquiry that, although the inner endosperm is undoubtedly 
capable of augmenting its amylase content, yet this phenomenon is unaccom¬ 
panied by any marked increase in the digestion of its starch reserves. The 
question has been further obscured by the apparent failure to recognize 
that the activity of amylolytic enzyme as measured by its action on soluble 
starch or starch paste does not necessarily parallel the activity of the same 
enzyme as measured by progress of its action on barley starch as it exists 
in situ either under the conditions of experiment described in this paper or 
under normal conditions of germination. 
If we are to gain information regarding the complex phenomena met 
with in the germinative processes we must as far as possible study the 
mode of action of the enzymes which induce the changes observed not only 
in vitro but also in situ. 
