144 ISABURO NAGAT: 
No, of 
Dye stuffs Conc. % Solvent days | Oryza Zea |\Hordeum 
steep. ae 
Thionine 0.1 dist. water 2 as = = 
” ” 50% ethyl alcohol 4 = is re 
> 0.05 50% methyl alcohol Er (+)? + 
a & dist. water 3 = uf 
” 0.1 50% methyl alcohol LA + 
Thionine + Coceinin 0.1 dist. water 3 = 
Thionine+ Light green 0.1 dist. water 3 _ 
Tropaeolin OO 0.05 47.5% ethyl alcohol 3 = 
» 0.1 95% > 2 =: 
Tropaeolin OOO 0.1 dist. water 1 we 
One of the interesting facts observed, however unimportant it may be in 
this connection, is the influence of the solvent on the permeability of the 
seed-covering. Fluorescein is an insoluble dye stuff in cold water, but easily solu- 
ble in hot water or in a cold weak alkaline solution, as well as in a strong 
alcohol solution. A weak ammoniacal solution (0.19%) of this dye does not 
pass through the septum, but does if applied in an alcoholic solution (dis- 
solved at first in a small amount of absolute alcohol and made up to a 
desired concentration by an addition of water). An aqueous solution of 
safranine (0.05%) is indiffusible, but its ethyl-aleoholie solution is diffusible. 
A concentrated aniline-water solution is also diffusible. The septum in Zea 
is permeable to methylalcoholic solution (0.05%) of gentian violet, Malachite 
green, methylene blue, methyl green, and thionine, but impermeable to the 
respective aqueous solutions. While that of Oryza is impermeable to either 
aqueous or to alcoholic solutions of gentian violet, Malachite green, methyl 
green, and methylene blue. 
The permeability of the seed-covering by the solvent is independent of the 
permeability by the dissolved dyes. For example, it is easily permeable to 
acetic acid but ‘impermeable to methyl green dissolved in a weak acetic 
acid solution, just as in the case with an aqueous solution. A distinct 
demarkation is made by the cuticular layer; above it is intensely stained 
and the underlying tissue is utterly without staining. Coceinin, Congo red, 
