ii 66 Stoward.—A my loclastic Secretory Capacities of the 
rift traversing it from apex to base. The above experimental results, how¬ 
ever, show that inclusion of dextrose in the culture medium inhibits the 
secretion of amylase in the tissues of the plantlet, for, as the above results 
indicate, the amount of amyloclastic enzyme in the embryos themselves is 
distinctly lower than in the controls. 
The following table furnishes data of physiological interest, the experi¬ 
ments, as already stated, being contemporaneous with those of Table XXX : 
TABLE XXXI. 
Cultures of Embryos on Asparagin-Mineral Salt Medium 
with Dextrose. 
Details of preparation the same as given in Table XXX. 
Nitrogen initially Residual Nitrogen as- N% in dry ~ ' ht f 
Exp. present in culture sugar in similated by plantlets weig oj 
medium. medium. plantlets. after culture . ^ em r ^ os ’ 
1. o*55 % asparagin- 14 mg. o-oo 14.8 mg. 10.05 r 47 
M.S. 1 % dextrose 
2. 1.1 % asparagin- 28 „ o-oo 20-5 ,, 11 *68 175 ,, 
M.S. 1 % dextrose 
The results furnish a rough idea of the manner in which assimilable 
nitrogen and carbon are removed from the culture medium. In Experi¬ 
ment 1, for example, both the total available nitrogen and carbon were 
absorbed, and in Experiment 2 a small residue of nitrogen only remained. 
The possible protective function to the secreted amylase, which has been 
ascribed by the author to asparagin, if exercised in these experiments and 
those comprised in Section III, evidently does not cover a very lengthy 
period of time. The complete removal of dextrose from the culture 
medium in these experiments leaves the question open whether the employ¬ 
ment of higher concentrations of this sugar would stimulate the embryo to 
exercise its secretory restrictive powers as fully as it does when cane sugar 
replaces dextrose. 
The foregoing results show that cane sugar and dextrose distinctly 
influence the amyloclastic secretory activity of the epithelial cells of the 
scutellum ; the presence of the former leads to the almost complete cessation 
of extra-cellular secretion, while the latter very considerably diminishes this 
phenomenon. Invert sugar, on the contrary, appears to be quite inert, 
secretion occurring in its presence in the particular concentration used, 
equally and to practically the same extent as when it is not included in the 
culture medium. 
Similarly conducted experiments were also carried out with dorsal 
fragments of aleurone layers prepared from seeds steeped in copper 
sulphate. 
These are summarized in the table which follows. 
