495 
Stomata in Halophytes . 
were detached from the parent plant and were probably transpiring at a rate 
appreciably greater than would have been the case had they been attached 
to a shoot bearing other leaves. This phenomenon has been observed by 
Pringsheim 1 in certain species of Sedum and other succulent plants which 
store up water in the adult leaves, and it seems probable that the same 
would apply to mesophytes, although this point was not determined. In 
the case of a species of Mesembryanthemum 2 observed by me, a detached 
adult leaf transpired per unit area from two to four times as freely when 
withering, as a shoot of the same plant under the same conditions, but bear- 
ing two young as well as two adult leaves. If this were true in the case of 
the Sedum and Vida mentioned in Table VI, it would make the contrast 
between the rates of transpiration in these cases only more strikingly 
remote from that of Salicornia annua. 
In Table VIII the proportional or ‘ relative ’ transpiration values are 
given for the three plants, taking the loss per hour per ioo sq. cm. in a freely 
evaporating water surface as ioo. The variations now shown in transpira- 
tion must be independent of the purely physical effect of the environment . 3 
TABLE VIII 
Relative Transpiration per Hour per ioo sq. cm. of Sedum, Salicornia , 
and Vicia. 
Sedum. 
Salicot'iiia annua. 
Vicia cracca. 
Water Surface. 
36 
3 2 
26 
IOO 
30 
28 
14 
IOO 
27 
36 
9 
IOO 
17 
26 
6 
IOO 
18 
23 
4 
IOO 
s 
N 
-\tt 
rn 
a 
\ 
►— 
>ec 
.un 
,t IL‘ 
jo 4-0 So go ioo 
Fig. io. Curves showing relative transpiration during withering of Salicornia , Sedum , and 
Vicia. Ordinates represent figures shown in Table VIII ; abscissae represent time intervals of 
20 minutes each. 
1 Pringsheim, E. (’ 06 ) : Wasserbewegung und Turgorregulation in welkenden Pflanzen. 
Jahrbiicher fiir wiss. Bot, 1906. 
2 Probably a variety of M. speciosum. 
3 Cp. Livingston (’ 06 ) : The Relation of Desert Plants to Soil, Moisture, and to Evaporation. 
