1894. ] Anatomical and Physiological Researches. 413 
tion of a tree is large in proportion to its conducting tissue, 
the wood of the tree will be composed largely of conducting 
and storage tissue; on the other hand, if the amount of trans- 
piration is limited to any considerable degree, less conduct- 
ing tissue will be required and the tree will have at its dis- 
posal a larger quantity of plastic material from which to pro- 
duce mechanical tissue. —L. S. CHENEY. 
Adaptation of African plants to climate. 
After some introductory remarks upon the highly interest- 
ing flora of Cape Colony, the author describes the different 
ways in which the plants are adapted to the climate. The 
Variety of arrangements for this purpose is very great and 
may be considered from different points of view. The evap- 
oration is prevented by reduction of the leaves, either by the 
development of small leaf-blades, or by transferring their func- | 
tion to green stems. Stapelia, Euphorbia and the imported ie 
Opuntia illustrate the last case, while small or narrow leaves 
are very common, for instance in Bruniaceez, many Compos- tg 
ite, and others. Some other plants show the surface of the = 
leaves impregnated with substances that are impermeable to 
Water, and this is to be observed in Aloe, Protea, Myrica and ae 
several others. The cuticle, or a cover of wax or silica, forms 
the protective medium in these plants. 
Secreted mineral substances may also form a protecting 
“yer over the whole leaf as in Tamarix, or only over the de=. me 
°selia, and other Plumbaginez. : nee 
; Such arrangements as the placing of the stomata in depres- : 
Pee OE crooves of ‘leaves ahd stems, or under the re xed a 
*dges of the leaves are also common in this vegetation. a s 
Eucaly ptus globulus and Protea grandiflora illustrate 4 
— 'n which the leaves assume the most favorable positi 
°Wards-the sun. ‘ ae 
“re are also plants which possess reservoirs in their stems, 
thizomes, or leaves. Such plants are the delicate herb, Ele- oh 
4 y # ke ‘ Nga 3 a Ai 
hag R.—Some adaptations of South African plants to the climate. — 
th African Phil. Soc. 6: 31. A ag 
