Permeability 
81 
Table XXXVI 
Absorption Ratios of Sulphonic Acid Dyes. 
(Data from Collander) 
External Duration 
concen- of ex- 
tration in periment Absorp- 
Species 
Tissue 
Dye 
per cent. 
in hours 
tion ratio 
Allium Cepa 
Parenchyma of bulb 
Light green 
o*8 
46 
<0-016 
Daucus Carota 
scale 
Root parenchyma 
Orange G 
o-8 
42 
<0-016 
Hyacinthus 
Cortex of root 
Cyanol 
o-i 
24 
<0-125 
orientalis 
Storage cells of bulb 
0*1 
24 
<0-125 
scales 
Parenchyma of pe¬ 
O'l 
24 
<0-062 
duncle 
Orange G 
o-8 
72 
<0-0078 
9J 
Bundle sheath of pe¬ 
} f 
0*012 
24 
>4-0 
Pisum sativum 
rianth leaves 
0-05 
24 
<0-25 
Cortex of root 
Cyanol 
o-8 
24 
<0-062 
Rhceo discolor 
Spongy parenchyma 
Orange G 
o-8 
48 
<0-062 
Spirogyra sp. 
— 
Cyanol 
o-8 
50 
<0-062 
,, 
-- 
Orange G 
o-8 
90 
<0-031 
— 
Fuchsin S 
o-8 
66 
<0-125 
It is clear then that the absorption ratios of dyes may vary within 
very wide limits, from many times unity in the case of most basic 
dyes, to less than o-oi in the case of some tissues immersed in 
solutions of acid dyes. 
With dead tissue the absorption ratios in the case of salts are 
much nearer unity (cf. Table XXXI). The maintenance of equilibrium 
with different concentrations inside and * outside the cell is thus a 
property of living tissue. 
It is interesting to note that the maintenance of an equilibrium 
in which the concentration of a substance inside the tissue is apparently 
different from that outside has also been observed in the case of 
seeds. Brown and Tinker (1916 b) soaked grains of barley in solutions 
of aniline, phenol and acetic acid, and determined the extent of the 
absorption of these substances by analysis of the seeds. They found 
that aniline and phenol accumulated inside the seeds so that the 
concentration of these substances inside the seeds was about three 
times as great as the external concentration. With acetic acid, on 
the other hand, equilibrium was attained when the concentration of 
the acid inside the seed was about 80 per cent, of the external con¬ 
centration, the latter being in the neighbourhood of 40 per cent, 
(the ratio acetic acid : water being between 0-5 and 0*9). 
Phyt. XXII. 2 . 
6 
