Aspects of Ecology. 
by Dr. Engler under the title of “ Die Friihlingsflora des 
Tafelberges bei Kapstadt (Noti/ber. des Kdnigl. botanischen Gartens 
zu Berlin, 1903). 
ECOLOGY IN ITS PHYSIOLOGICAL AND PHYTO¬ 
TOPOGRAPH ICAL ASPECTS.—A Review . 1 
By F. F. Blackman and A. G. Tansley. 
(Continued from page 2 03). 
ROM the foregoing examination of the scope and aims of 
Ecology we turn to consider its methods and procedure, more 
particularly those in the comprehensive scheme drawn up by Dr. 
Clements, by which the intentions of Ecology are to be realised. 
The ecological investigator in the midst of vegetation finds 
himself in the presence of a state of equilibrium between the 
organized and the unorganized, between “The Habitat” of the one 
part and “The Formation” of the other part, the latter coter¬ 
minous with and interpenetrating the former, and consisting of 
the congeries of ecads 2 and species characteristic of the given 
habitat. Such equilibrium may well stimulate analytical enquiry 
into its nature. 
The Habitat can be analysed into physical factors such as 
water-content of soil, humidity of air, light, temperature, chemical 
composition of soil, wind, altitude, etc. The problem before the 
investigator here is to determine which arc the essential factors 
affecting vegetation and to provide a satisfactory method for 
measuring each. Consideration of this branch of the enquiry 
occupies Chapter II. of Dr. Clements’ book. 
“The Formation” as an organic whole is dealt with in Chapter 
IV., while “The Plant” as the unit of the Formation occupies 
Chapter III. The Plant, like the Habitat, can also be analysed,and 
reveals innumerable structural details. Certain structural attributes 
of plants may be traced directly to the common attributes of pro¬ 
toplasm, others are cosmopolitan and not characteristic of any 
habitat, or due to inheritance, irrelevant to the habitat. A cor.si- 
1 “ Research Methods in Ecology.” By F. E. Clements, Ph.D., 
Associate Professor of Plant Physiology in the University of 
Nebraska. Pp. XVII. and 334. 85 Figures in the text. 
S3. Lincoln, Nebraska, U.S.A. 
2 An “ ecad is a habitat form due to origin by adaptation,” 
