Observations on Behaviour of Turgescent Tissue. 59 
comparison is legitimate between curves obtained in the same 
experiment with material from the same tuber. 
Adjacent rectangular pieces of approximately the same size 
and shape, or cylindrical pieces of equal length were cut from the 
interior of a tuber, blotted, weighed, put into water or solutions, 
and thereafter blotted and weighed at intervals. The initial weight 
of the pieces taken was in most cases between 4 and 5 grammes. 
All the results have been calculated as percentages of the initial 
weights and plotted against the time. In a final analysis, however, 
it would be a point for consideration whether unit weight or unit 
surface area would be the more satisfactory basis. 1 The method of 
Stiles and Jorgensen has the advantage that, in addition to reducing 
the sampling error, it secures a close approximation to equality 
both of weight and of surface. 
Limits of Error. The results given in the following table show 
the degree of correspondence obtained when similar pieces of tissue 
were treated in the same way. The data are those on which Fig. 3 
is based, confirming a result with M/100 mercuric chloride solution 
to be mentioned later. 
Initial weight in grms. 
Gain in weight 
in gms. 
Percentage gain in weight. 
30 mins. 
63 mins. 
93 mins. 
30 mins. 
63 mins. 
93 mins. 
In distilled water. 
2-579 
0 078 
0-142 
0-172 
30 
5-5 
6-7 
2-580 
0-090 
0.154 
0-190 
3-5 
6-0 
7-4 
2-561 
0-085 
0147 
0-188 
3-3 
5-7 
7-3 
2-600 
0 089 
0-164 
0-210 
3-4 
6-3 
81 
Mean + probable error 
Maximum difference 
3-3+ 0-1 
5 9 + 0-1 
7-4 + 0-2 
from mean 
0-3 
0-4 
0-7 
In MjlOO mercuric chloride. 
2-620 
0 093 
0122 
0-121 
3-5 
4-7 
4-6 
2-526 
0-094 
0-132 
0133 
3-7 
5-1 
5-2 
2-580 
0-110 
0-143 
0146 
4-3 
5-5 
5-7 
2-631 
0 116 
0-151 
0-153 
4-4 
5-7 
5-8 
Mean + probable error 
Maximum difference 
4-0 + 0-2 
5-2 + 0-2 
5-3 + 0-2 
from mean 
0-5 
0-5 
0-7 
Cane Sugar. 
Experiments were first made with various concentrations of 
cane sugar, to obtain curves illustrating the simple osmotic entry or 
' Cf. Stiles and Jorgensen’s discussion of this question and their test 
experiments, in connexion with the exosmosis of electrolytes. “ Studies in 
Permeability IV,” Annals of botany, XXXI, 1P17, pp. 52-3. 
