1397,] Vegetable Physiology. 435 
VEGETABLE PHYSIOLOGY. 
Ecological Plant Geography.'—Plant geography can be con- 
sidered from two standpoints. First, floristic plant geography, which 
treats of the flora of a region, a list of the species growing within certain 
geographical limits, the relative proportion of certain species, the rela- 
tion of an insular flora to that of the mainland, or of a mountain flora 
to that of the adjacent valleys; that is, facts concerning distribution. 
Secondly, ecological plant geography, which treats of plant communi- 
ties as resultants of all the forces working upon them. 
The ordinary observer has no difficulty in noting that the plants over 
one area are different from those over another. He distinguishes the 
swamp, the meadow, the scrub, the pine-barren, the prairie, and other 
equally well-marked plant communities. What he notices, however, 
may not be that certain species of plants grow in one area and certain 
other species in another, it is rather the general appearance of the area, 
that is, its physiognomy. It is not a difficult matter to determine the 
species which are associated to form a certain plant community with its 
corresponding physiognomy. A more difficult question to answer is, 
however, “ Why do these species unite into certain communities, and 
why have they the physiognomy which they possess?” 
It is the task of the author in the 382 pages of the book before us to 
solve these questions. The author lays down a few geueral principles, 
some of which I cannot refrain from giving. “ Every species must con- 
form, both in inner and outer structure, to the natural conditions under 
which it lives, and if, when those change, it cannot adapt itself to them, 
it will be crowded out by other species, or become entirely eliminated. 
It is, therefore, one of the first and most important problems of ecologi- 
cal plant geography to understand the epharmosis [die Epharmonie, 
epharmonie] of the species, or what can be called its life-form [ Lebens- 
form]. This is shown especially in the configuration of the plant and 
in the duration of the [so-called] organs of assimilation (in the structure 
of the leaf and of the entire sprout, in the life period of the individual, 
etc.), and to a less degree in the reproductive orgaus. This problem 
leads one far into morphological, anatomical and physiological studies ; 
it is very difficult, but very attractive. It cannot be entirely and satis- 
factorily solved, but much can be done in the future. 
1 Lehrbuch der Ockologischen Pflanzengeographie. Dr. Eugenius Warming. 
Translated from the Danish by Dr. Emil Knoblauch, 1896, Berlin, Gebriider. 
Borntreger. 
