Delf. — Transpiration in Succulent Plants . 
429 
Table VI. 
Water Content in successive pairs of Leaves of Gasteria vittata. 
Water Content 
Water Content 
Loss during 
drought. 
% of turgid 
leaves. 
% of withering 
leaves. 
First Pair (lowest) 
86.3 
78.6 
7*7 
Second Pair 
9°*3 
82.8 
7-5 
Third „ 
90-8 
83-7 
7-i 
Fourth ,, 
91. 1 
84.9 
6*2 
Fifth „ 
9 I *3 
86-o 
5*3 
Sixth „ (youngest) 
93*4 
91-8 
i*6 
In the case of Mesembryanthemum edule a shoot was chosen which had 
three pairs of expanded leaves and one very small pair, the leaves of which 
were closely appressed to each other. One leaf of each of the three pairs 
of expanded leaves was marked with Indian ink along the length and 
breadth of both upper and lower surfaces. The cross-section of one of 
these leaves forms an isosceles triangle, so that the marks on the lower 
surface were made on one flank only. The measurements were made with 
an accurately divided rule and a lens magnifying ten times. The shrinkage 
observed calculated as percentages is recorded in Table VII. 
Table VII. 
Shrinkage in Surface of Mesembryanthemum edule when withering. 
1 st day . 
% 
2nd day. 
% 
3 rd day. 
% 
6 th day. 
V 
7 th day. 
Length 
4.6 
✓O 
o-3 
/O 
2.4 
/o /o 
(Shrinkage had 
Upper Surface 
obliterated 
Lowest 
Breedth 
3-4 
3*6 
i*9 
marks.) 
Leaf. 
Length 
7*4 
0 
0 
Lower Surface 
Breadth 
3*3 
0 
0 
Length 
0 
i*i 
0 
5*6 
27 
Upper Surface 
Second 
Breadth 
1 9 
o*9 
0 
12 
2-2 
Leaf. 
Length 
1.8 
0.7 
0*3 
4.6 
i*6 
Lower Surface 
Breadth 
0 
0 
0 
0 
5 
Length 
0 
0 
0 
4'° 
i'3 
Upper Surface 
Third 
Breadth 
0 
0 
0 
10 
0 
Leaf. 
Length 
0 
0 
0 
Lower Surface 
(marks illegible) 
Breadth 
0 
0 
0 
It may be seen that the upper leaves were entirely, and the middle 
pair almost entirely, protected from loss in water content during three days’ 
exposure to warm, dry air. After the third day the lowest leaves shrivelled 
rapidly, turning yellow, and finally becoming mere empty shrivelled bags ; 
during this time the second pair of leaves first began to suffer seriously, 
