Embryo and Aleurone Layer of Hordenm . 1163 
these carbohydrates exercises on the phenomenon of regulative secretion by 
the isolated embryo. 
In the following table examples are given of the regulative control the 
embryo exercises over the amyloclastic secretory function of the columnar 
epithelium:— 
TABLE XXVIII. 
Influence of Cane and Invert Sugar on the Amyloclastic 
Secretory Function of the Embryo. 
African barley. Seeds steeped in io % CuSC^ 1 24 hours, water 24 hours. 
Exp. 
Culture medium. 
Duration of 
cultnr . 
Digestion 
period. 
Amylase per 20 objects 
per hour in mediu?n 
(equivalent to mg. Cu). 
1. 
M.S. + 5 % cane sugar 
8 days 
20 hours 
2-0 
2. 
0*55 % asparagin-M.S. + 5 % cane sugar 
4 » 
O I 
2 2 » 
0.00 
3- 
0-55 % asparagin-M.S. + 5 % invert sugar 
7 „ 
1 hour 
156-7 
There can be little doubt that in presence of cane sugar, in close 
agreement with the observations of Brown and Morris, the embryo restricts 
its amyloclastic secretory powers in a very marked degree. Invert sugar, 
on the contrary, as Experiment 3 shows, is almost without influence on the 
exercise of this function of the embryo, amyloclastic enzyme being secreted 
just as rapidly and freely as when it is not included in the culture medium. 
The embryo, as we shall see, when the medium contains dextrose, exercises 
its regulative powers and reins in the activity of the secretory epithelial 
cells, but not to the same extent as in the case of cane sugar. 
As the cultural experiments of Katz (loc. cit.) indicate, the secretory 
functions of Peniciliumglaucum, Aspergillus niger , and Bacillus megatherium 
are influenced by different carbohydrates in varying degree, depending on 
the particular carbohydrate and its concentration. 
The foregoing experiments and those which follow similarly demon¬ 
strate that the barley embryo adjusts or regulates its secretory powers; 
these vary with the carbohydrate employed, and, no doubt, with its con¬ 
centration, although this aspect of the subject has not been experimentally 
investigated. 
The data in Table XXIX below relate to cultures of embryos from 
seeds (Chilian barley) steeped successively in absolute alcohol and water 
under the customary conditions. 
Two contemporaneous cultures of forty embryos each, the one on 5 % 
gelatine-mineral salts (control), the other on the same kind of medium 
1 The steeping of material in this reagent does not seriously interfere with the subsequent growth 
and secretory activity of the embryo (see Section XIII: Inadmissibility of CuS0 4 as Sterilizing Agent), 
