8o 
Walter Stiles 
Nathansohn’s and Meurer’s experimental results. In Table XXXV 
are shown a selection of these absorption ratios. 
Table XXXV. 
Absorption Ratios 
External 
Duration of 
Absorption ratio 
concen¬ 
absorption 
( - 
Tissue 
Salt 
tration 
in days 
Ration 
Anion 
Codium 
NaNO a 
o *5 % 
4 
— 
0-56 
,, 
,, 
,, 
10 
— 
o-68 
,, 
,, 
1-0 % 
5 
. — 
0-44 
Dahlia 
,, 
,, 
4 
o -59 
9 , 
,, 
,, 
6 
0-51 
— . 
NH.NOg 
i '5 % 
4 
0-32 
— 
Carrot 
KC 1 
N/15 
4 
0-548 
0-386 
,, 
NaCl 
N/i 2 
4 
0-489 
0-307 
It will be observed that in scarcely any case does the absorp¬ 
tion ratio approximate to unity, although having regard to the fact 
that thin slices of tissue were used and that the salts employed 
have fairly high coefficients of diffusion, the equilibrium condition 
could not be far off at the end of the experiment. This is also indicated 
by the value of the absorption ratio at the end of, say, four days, 
being practically identical with that at the end of six days in the 
case of the absorption of sodium nitrate by Dahlia tuber. 
It can therefore scarcely be argued that as all these absorption 
ratios are less than unity the reason for this is that equilibrium had 
not been reached when the experiments were brought to a conclusion. 
Moreover, in the case of the absorption of aluminium sulphate by 
carrot and other tissues Meurer found so great absorption of the 
aluminium ion from a 0-056 per cent, solution that the absorption 
ratio with carrot after two days was 11-33 and after four days 16-89. 
Of course, aluminium may be a special case, and Meurer himself 
thought it was absorbed by the cell walls. However, as we shall see 
shortly, there is no reason from the high value of the absorption 
ratio to suppose that the behaviour of aluminium is exceptional. 
In this connexion the results obtained with dyes are interesting. 
Reference has already been made to the work of Pfeffer and others 
who have shown that in the absorption of many dyes there is a 
considerable “heaping up” of the dye in the tissue. This is chiefly, 
though not exclusively, a property of the so-called basic dyes, and 
Collander (1921) has shown that a number of sulphonic acid dyes 
are only absorbed to a comparatively small extent by many plant 
tissues. Some of the absorption ratios found by him are collected 
in the following table. 
