304 5 BOTANICAL GAZETTE {octoER 
tation to the heterogeneity of the earth’s surface, and is in sharp contrast to zona- 
tion as it is related to topographic asymmetry. A very interesting analysis is 
made of competition, which the author holds to be a physical factor in the last 
analysis. 
This book is most difficult to review adequately, because of the great num- 
ber of vital topics which are presented. The presentation is so logical and con 
cise that a satisfactory review or summary would be little less than a verbatim 
reproduction of the work. The paper must be digested thoroughly from begin- 
ning to end by all who profess to be engaged in ecological research, and it should 
be studied by all botanists, especially those who think that ecology may not hope 
to deal with facts or have the logic or discipline of other lines of biology—H. © 
COWLES. 
Leaf ecology. 
HanscirG, who for a considerable time has been gathering data for such 
a work, has issued a somewhat elaborate volume on phyllobiology.? The am 
of the author is to present the topic of the biology of the leaf, much as the biology 
of the flower has been presented in earlier works. Part I is devoted to a general 
consideration of leaf adaptations, especially those adaptations that may be called 
protective. Parts II and III make up the body of the volume, and present the 
biological classes or types of leaves. 
Two general groups are recognized: the water and swamp leaf types of hydro 
phytes and halophytes, and the air leaf types of land plants. The former grou? 
has six subdivisions: the Vallisneria type adapted to currents, the M 
type adapted to standing water, the Nymphaea type of floating leaves, the Is 
type, the Lysimachia (Naumburgia) type, and the Calla type. More o 
types of air leaves are given, among which the following may be noted, - . 
illustrate the method of the author: the violet type of shade leaf, the ie 
type (wedge-shaped at base), the Taraxacum type of rosette leaves, the a" 
type of liana leaves, the Cyclamen type (reddish beneath), the Begona type 
type of trembling leaves, the Allium type of tubular leaves, 
of weather-vane leaves, the conifer type of needle leaves, the ; 
profile leaves, the grass type of involute leaves, the Gnaph j ou the Cat 
leaves, nyctitropic leaves, the Mesembrianthemum type of thick whey cast 
duus type of spiny leaves, the Drosera type of insectivorous leaves. roger with 
there is a detailed description of the leaf type under consideration, hich isa 
a discusion of the ecological advantages of the type. The pee 
the types are given in considerable detail. t is by past 
Part III considers the same material, but the age ee of youss 
families and genera. Part IV considers the protective ee ve 
2 Hanscire, A., Phyllobiologie nebst Uebersicht der biologic a a 
ein-und-sechzig Siphonogamenfamilien. 8vo. pp- xiv+ 486. es 4 
der Borntraeger. 1903. Mrz. : 
