834 Stoward.—Amyloclastic Secretory Capacities of the 
In the following series of experiments, Experiment 4 calls for special 
notice because it was designed to show, under conditions which are strictly 
comparable as regards external circumstances, the very different behaviour 
of the two halves of the endosperm under the following conditions :— 
The dorsal portion of the aleurone layer was completely removed from 
each endosperm, and the latter was divided into two longitudinal halves by 
a plane traversing it midway between its dorsal and ventral halves ; on each 
plate, therefore, in Experiments 3 and 4 there are ten dorsal halves of endo¬ 
sperms deprived of their aleurone layers, and ten corresponding ventral 
halves with their aleurone layers still adherent. 
The numerical data furnished by these experiments are embodied 
in the following table :— 
TABLE XVIII. 
Cultures of Endosperms on o-8 % Agar-Mineral Salts (P*). 1 
Chilian barley. Culture period, 19 days. Seeds 48 hours absolute alcohol, 48 hours water. 
Exp. 
Objects. 
Amylase per 
Medium. 
20 in :— 
Objects. 
Reducing sugars 
in medium 
(equivalent to 
mg. of Cu). 
(.equivalent to mg. of Cu.) 
1. 
10 endosperms (whole) 
0-00 
620 
378 
2. 
10 endosperms (halved) 
0.00 
698 
543 
3 - 
10 endosperms deprived of dorsal aleurone 
0*00 
124 
494 
layers 
4 * 
10 endosperms, halved, and dorsal halves de¬ 
0-00 
232 
378 
prived of their aleurone layers 
Just as in the experiments of Table XVII, there is a considerable 
amount of reducing sugar present in the culture medium in each experi¬ 
ment. The absence of amylase in the culture medium in this series 
apparently turns on the presence of the higher concentration of KH 2 P 0 4 
employed. Whether this reagent is operative in the culture medium or 
during digestion with soluble starch is undecided and remains a question 
for future investigation. 
The results show on the one hand (Exps. 3 and 4) that even when the 
area of the aleurone layer is reduced to practically one-half its original 
extent, and the reduction in the area of the amylase-secretory tissue is very 
considerable, the amylolytic activity of the remaining secretory tissue 
is still able to effect a considerable amount of transformation in the starch 
storage materials, as shown by the quantities of reducing sugars in the 
medium of these experiments. 
It is, however, the macroscopical and microscopical features presented by 
the ventral and dorsal halves in Exps. 3 and 4 which require mention. 
The former show the usual phenomena, already enumerated in the 
case of endosperm cultures : reduction in the mass of and rounding off 
1 Concentration of KH 2 P 0 4 fourfold. 
