PHYSIOLOGICAL ANIMAL GEOGRAPHY 555 
of the biological type, the most noted of whom were contempo- 
raries of Darwin, such as Bates, Belt, Wallace and Brehm. Though 
anthropomorphic, at least in his wording, Brehm stands as one of 
the foremost writers of the time in this field of animal behavior. 
He had unusual power as an observer of the habits of animals. His 
particular excellence is his power of observing and picturing animal 
life as it is lived in nature, without taking account of which biology is 
a mockery and any theory of evolution a one-sided dogma. The success 
of the pictures which Brehm has given us of bird-bergs and tundras, 
of steppes and desert, of river fauna and tropical forest, raises the wish 
that they had been complete enough to embrace the whole world. 
Thomson. 
An excellent discussion by Craig (’08) who compares the be- 
havior and adaptation of the birds and mammals of the steppe of 
North America with those of the forest,? is the only recent paper 
of this kind, by a zoologist, which has come to my attention. 
There has been, so far as I have found, no comparison of the 
behavior of the animals of the different deserts or different 
steppes, etc. 
While physiological animal geography is a subject for experi- 
mental study, experimental methods can hardly be said to have 
been used in the study of geographic distribution. Experimental 
researches which have involved distribution are limited chiefly 
to investigations of the reactions and local distribution of aquatic 
and cave animals (Banta, 710). 
In the field of plant geography, Schimper’s (’03) work indicates 
the first step in the development of the world-wide aspect along 
physiological lines (Cowles, 09). This work opened a new and 
fruitful field for experimental work and field observation. Here 
Warming (’09), Cowles (’01), Whitford (’01), Transeau (’03, ’95) 
and others contributed much from the observational side, while 
others have done important experimental work. 
In the presentation of data and in the discussions here we 
illustrate two points of view for investigation by classifying the 
materials roughly into (a) those related primarily to the par- 
®’ The work of Adams (’05, ’09), and Ruthven (06), was conducted with refer- 
ence to all the animals but from a genetic rather than a physiological point of 
view. 
