— 208 — 
internally up to a certain specific maximum varying for 
different species, and that in this physiologically determined 
limitation of salt storage they have a sufficient means for 
securing the high osmotic pressure which FirriNG has pointed 
out in the desert-plants and which enables them to obtain 
water from the soil. In addition to sodium chloride, there 
is also excretion of carbonate of lime often in great quanti- 
ties, so it is not at all certain that the excretion of sodium 
chloride is of any special importance. And finally FirTine 
points out that dew is exceedingly rare in the Sahara. 
The flowers of Reaumuria are large and terminal on the 
branches, they appear in July. Below the calyx there are 
several bracteoles forming an involucre. The fruit is a 
capsule with about a score of white woolly seeds. 
The leaf anatomy of Reaumuria oxiana has been briefly 
described by VESQuE. The thick epidermis consists of one 
layer, and the stomata and salt-glands are depressed. The 
leaf is isolateral with about two layers of palisade cells and 
a central water-storing tissue. Between the green tissue and 
the water-storing tissue, or amongst the palisade, are numer- 
ous bands of sclerenchyma running longitudinally within the 
leaf, and from these issue long, thin sclerenchyma-cells 
which as idioblasts stretch through the palisade to the 
epidermis as if to support it from the inside (fig. 46 A C; 
also VESQUE tab. 8, fig. 7). 
Reaumuria fruticosa Bge. 
On moderately stable sandy soil I have found shrubs 
of this species scarcely attaining the height of one metre. 
It is strongly branched, the branches being strikingly 
thick and light in colour. The year-shoots may attain a 
length of 5 centimetres, and apparently always die back at 
the apex, which remains as a dry stick. Branches of two 
different kinds occur on the year-shoot, some are short but 
quite evidently branches with elongated internodes, others 
are rosette-like short-shoots. The former may be wanting, 
but when present they are generally placed towards the apex 
of the year-shoot. They are rarely 2 centimetres long, gener- 
