SOME STUDIES ON THE GERMINATION OF THE SEED OF ORYZA SATIVA. 139 
parenchyma of the pericarp and the aleurone layer, suggesting the presence 
of a pectine substance. A thin cuticula layer is found at the upper 
epidermis of the pericarp and a thick layer at the inner wall of the inner 
integument. 
The cell wall of the spermoderm is dissolved by the addition of con- 
centrated sulphuric acid, except the cutinized layer. 
As already referred to, the cuticula layer in the matured grains appears 
to lie directly above the aleurone lvyer, but in maceration by a strong solu- 
tion of sulphuric acid with iodine, the cuticula and its component cell wall 
is separated, the former being colored brown, and the latter dissolving in a 
deep blue colour. A weak solution of natrium hydroxide easily destroys the 
seed-covering, especially along the vascular bundles which lie along the 
dorsal ridge of the grain, 
The fact that the cutinized layer of the inner integument withstands the 
action of strong acids, leads to an assumption that this layer may be the 
seat of the selective permeable septum. SCHROEDER (1911) has already ex- 
pressed this view. ‘The Oryza grains are steeped in a strong sulphuric acid 
or hydrochloric acid solution for 24 hours and then thoroughly washed. <A thin 
section of the treated grains is mounted on a slide with a drop of Congo 
red or orange G. The section shows, that the acid penetrates the tissue 
which lies above the cuticula layer, but in the tissue which lies below the 
cuticula, no acid reaction is observed. 
Furthermore, the results of the experiments with the dye solutions sup- 
port the above assumption. A majority of the dye stuffs studied, dissolving 
in various solvents with various concentrations, stain only the tissue above 
the cuticula layer of the integument, but the underlying tissue remains un- 
stained. In most cases, a sharp demarkation is made at the cutinized 
layer. The dyes used for the experiments are the following. Those which 
are marked with signs are known as vital staining ones. 
Gentian violet*§ Dahlia* 
Malachite green F.S.*t Methyl green*$} 
Aniline blue* Light green S. F.+ 
Thionine* Bismarck brown*§ 
* by Overron (1900), $ by Prerrer (1886), + by Runtaxo (1912), } by Hözer (1909). 
