286. BOTANICAL GAZETTE [Marce 
the fluids from the leaves of woody as compared with those from herbaceous 
plants, and (2) that the sap concentration shows a variation corresponding to 
‘the xerophytism of the plant community from which the fluids are obtained. 
The importance of the latter relationship has been given emphasis in a 
paper which gives a summary of results concerning large and widely differing 
plant formations. Here it is seen that the concentration of the cell sap of 
the woody plants varies from 11.44 atmospheres for that from the rain forest 
and 14.4 for that from mesophytic habitats to 24.97-30.05 atmospheres for 
the fluids of desert plants. Herbaceous plants from these same habitats show 
sap concentration values of 8.80, 10.41, and 15.15 atmospheres respectively. 
As — be expected, succulent halophytes show even higher concentrations, 
culminating, perhaps, in 49.7 atmospheres for Batis maritima. Curiously 
enough, oe epiphytes of the rain forest show concentrations of a low order, such 
as 3.34-4.88 atmospheres for the epiphytic Orchidaceae from Jamaica and 
se and other similar results are sufficient to demonstrate that in this 
line of investigation there has been found a means of expressing in a quantita- 
tive manner the sap properties of both large and small plant communities; 
hence not only must the results themselves be regarded as important, but a 
much higher value must be placed upon the introduction of a method which 
will tend to exactness in studies of the physiological plant geography.—GE0. 
. FULLER. 
Natal vegetation.—In advancing our acquaintance with the vegetation 
of South Africa, Bews® has made a study of the species native to Natal accord- 
ing to RAUNKIAER’S life-forms, and has expressed the results in a biological 
spectrum for that part of South Africa. Some of the conspicuous features of 
the vegetation as shown by this analysis are the richness, manifest in more than 
geophytes. One of the interesting incidental features of the vegetation con- 
sists in the presence of stem succulents, all See: a milky juice, as they 
belong to the Asclepiadaceae and Euphorbiac 
In a more recent paper, the same cide hes described the vegetation of 
the mountains forming the western boundary of Natal and reaching an altitude 
of 3400m. The outline of the plant communities involved shows that grass- 
land and scrub associations predominate. Of the latter, the one developed 
3 Harris, J. Re Re tesa chemistry in the service of phytogeography. 
Science N.S. 46: 25-30. 
32 Bews, J. W., is tae forms of Natal plants. Trans. Roy. Soc. S. Africa 
5:605-636. 1916 
3b “The plant ecology of the Drakensberg range. Annals Natal Museum 
32511-5065. 1917. 
