ECOLOGICAL WORK IN BOTANY. 
205 
Finally, our work has suffered at the hands of those who under¬ 
took it without sufficient foundation knowledge to enable them to 
interpret intelligently the biology of the plant in its habitat. He 
is a well trained and cautious observer who can perceive the 
agencies which mould the structure or habits of a plant growing 
in its native environment; not all skilled laboratory workers do 
it successfully when they go to the field. But the field worker 
must, above all else, be familiar with the morphology and physi¬ 
ology of the plant through the laboratory method; for unless he 
perceives the various activities by which the plant maintains its 
existence and bodily form when he can, in a measure, isolate 
them in a laboratory, he will be less able to do so in the field. 
It is gratifying to know that the former practice of theorizing 
is giving way to experimental field work; for it indicates that the 
workers realize that practically all ecological studies are ulti¬ 
mately physiological. 
By way of giving a general view of the ecological work in 
botany of the last hundred years, the writer has divided it into 
three periods. They are not, of course, sharply marked off from 
each other; but they are intended to show certain manifest ten¬ 
dencies in the work. 
Period I. 1803-1859. A study of the distribution of plants 
based on the laws of meteorology and temperature control. , 
Period II. 1859-1885. Two distinct tendencies appear in 
this period which may be designated— 
(a) Biological. The adaptations of plants for pollination, cap¬ 
ture of prey, seed dispersal, etc. 
( b ) Distributional. The study of plants on the earth accord¬ 
ing to the conditions of the natural divisions. 
Period III. 1885 to the present. The study of the adapta¬ 
tion of the plant to its internal and external environment. The 
physiological response to the complex of factors operating upon 
the plant. 
