310 BOTANICAL GAZETTE [APRIL 
is especially significant. From an exhaustive study of local floras he has drawn 
circumpolar biochores, connecting regions with similar proportions of chamae- 
phytes. The biochores of ro per cent, 20 per cent, and 30 per cent are chosen 
to separate four floral zones, which he distinguishes as follows: a cold temperate 
or hemicryptophyte zone, south of the ro per cent biochore 3a boreal zone, 
between the 10 per cent and 20 per cent biochores; an arctic zone, between 
the 20 per cent and 30 per cent biochores; and an arctic-nival zone — 
the 30 per cent line. The same methods are also applied to alpine floras, an 
the number of chamaephytes is found to increase in the same way with ae 
altitude. RAUNKIAER’s chief object is apparently the recognition of certain 
types of climate, the results of which are expressed in the vege ad 
methods will probably have a much greater value in characterizing Ho 
regions, irrespective of their climate, and will have the great vee 
basing the distinctions between regions upon the plants themselves, rat 
than upon any physical feature of the environment. It remains to be see 
whether his chief biochores, chosen at certain round numbers and from one 
life form only, wi tually prove to be the most important.—H. A. CA 
Gas movement.—Ouno" has uncovered a most interesting situation in the 
rapid gaseous output from the leaf of Nelumbo nucifera. It is borne es 
distance above the water, and in the*central region over the petiole — 
a considerable depression. If on a warm sunny day one places some a 
in this depression, he will see a rapid extrusion of gas, which amounts to my 
times the volume of the leaf in a relatively short period. Analysis shows 
the gas contains the percentage of O, found in air. A like volume is “ss 
by a detached leaf with its petiole in water, even in darkness if the uppet = 
face is warmed. All these facts show that it is not O, produced by pu 
thesis, and indicate that it is air. Any condition that keeps the air ie 
leaf dry, sets up such an extrusion of gas. The phenomenon is best ~ ere 
by the behavior of a model made by Oxwo, which he states 1s a modi cat ue 
of forms before used, to show, in other connections, the physical princiP 
which he believes is applicable here. ee 
A porous clay sie filled with moist sphagnum and the open end a 
with a one-holed rubber stopper and glass and rubber tubing. The en ’ i 
latter dips just a little under the water. The porous cup is heated pense 
a warming stage. The air begins streaming out of the tube and con a 
until it amounts to several times the volume of the porous cup. It rua ; 
when the water supply of the sphagnum is exhausted. The air on the “— 
of the tube is relatively dry and the gas pressure there is mainly air. pees 
there is a considerable water vapor pressure which decreases the air ae ie 
For this reason there is an inward diffusion of air, and, according to the Be a 
law, an even more rapid outward diffusion of water vapor. The os a 
vapor is constantly resupplied by the moist sphagnum. ‘There res 
" Nelumbo 
© Onno, N., Ueber lebhafte Gasausscheidung aus den Blattern von 
nucifera Gaertn. Zeitschr. Bot. 2:641-664. Igio. 
