504 Delf . — Transpiration and Behaviour of 
Sedum acre and of Sedum albtim are similarly unprotected and mesophytic 
in character, and these plants also show a high rate of transpiration per unit 
area. In the course of these experiments the epidermis of plants of Suaeda 
maritima has often been examined, but the stomata have never been found 
open ; the same is true of the minute stomata of A triplex portulacoides , 
which are further protected by a scaly covering of epidermal hairs. 
Summary and Conclusions. 
In the course of this paper it has been shown that : — 
1. Salicornia annua and Suaeda maritima , both typical halophytes, 
have a high rate of transpiration per unit of surface area which is com- 
parable with, or even greater than, that of a typical mesophyte, such as 
Vicia faba. 
2 . The transpiration rates obtained for these plants are not necessarily 
maximal, since no precaution was taken to ensure that the plants were abso- 
lutely turgid initially, and that the stomata were open ; probably with 
wholly favourable conditions a still more rapid loss of water would ensue. 
The extent to which the rate of transpiration varies with the age of the 
plant has not yet been determined. 
3. When not already turgid these plants are able to absorb water 
freely over their whole surface ; in this respect they resemble certain meso- 
phytes, such as species of Plantago and Rumex. They have, however, 
unlike mesophytes, a certain capacity for storing water. 
4. The stomata in Salicornia annua and in Aster tripolium are not 
sunken and are not protected by cuticle to any extent ; they have a distinct 
power of movement, and close in darkness. The stomata of Salicornia 
appear to lose their power of movement after the flowering period, and 
then remain permanently closed ; those of Aster tripolium were also sen- 
sitive to the relative humidity of the atmosphere, being found open in the 
month of September in air nearly saturated with water vapour, and closed 
shortly afterwards on the same plant in air of 75 % relative humidity: in 
winter this power of movement diminishes, or perhaps completely dis- 
appears. 
5. Observations on the transpiration and stomatal behaviour of other 
halophytic plants are needed before any conclusions applicable to the whole 
group of plants can be made. 
References. 
Aubert, E. (’ 92 ) : Turgescence et Transpiration des Plantes grasses. Ann. des Sci. Nat., 1892. 
Henslow, Rev. George (’ 08 ): The Absorption of Rain and Dew by Green Parts of Plants. 
Journ. Roy. Hort. Soc., London, T908. 
Jost, Dr. L. (’07) : Lectures on Plant Physiology. English Edition, p. 97. 
