136 ISABURO NAGAT: 
These factors may act independently or combined according to the case, so 
that the selective septum plays only a part, which, however, can by no 
means be overestimated. 
II. The Seat of the Selective Permeable Septum 
in the Seed Covering. 
In spite of the fact that the selective permeability displayed by the seed 
is well marked, the localization of the septum in the seed covering is not 
quite definitely known. Brown (1907, 1909) considers, that in the case with 
Hordeum vulgare var. caerulescens, the selective power is confined to the 
testa, and probably to that portion which is derived from the epidermis of 
the nucellus during the development of the seed. He studied the limit of 
penetration by treating the grain with a solution of silver nitrate for 48 
hours, then in a solution of sodium chloride. The precipitation of silver 
chloride in the tissue and the subsequent blackening on exposure to light 
makes the limit of penetration visible. By this method, he found that a part 
of the spermaderm is colored, but a thin layer of uncolored membrane 
remains between the stained portion and the walls of the aleurone cells. 
SCHROEDER (1911) thinks, however, that in the wheat grain, it is the cutinized 
or lignified inner integument, instead of the epidermis of the nucellus, which 
gives the typical cellulose reaction and dissolves promptly in concentrated 
sulphuric acid. The present study in Oryza agrees with SCHROEDER’s obser- 
vation on Triticum, namely, that the selective permeable septum in the seed 
of Oryza is the thickly cutinized inner wall of the inner integument, and 
probably the case is also true in Zeu. 
It is highy desirable to obtain, at the outset, a definite knowledge in 
the anatomy of the seed coat, but unfortunately the descriptions given by 
previous authors disagree. According to Voct (1899) the pericarp (“ Silber- 
häutchen ”) of the rice grain consists of (1) “ Epidermis”, (2) “ Schwamm- 
parenchym ”, “ Querzellenschicht ”, and (3) “ Schläuche ”, but the true seed coat 
is not observable (,, Samenhaut als besondere Zellschicht ist noch nicht nach- 
weisbar “). The figure that he gives (p. 130) appears to be quite different 
from what we actually observe in our material. Owarı (1902) gives a some- 
