PRESIDENTIAL ADDRESSES. 29 
minerals, is on one side and the more concentrated cell sap is on the other, A 
current is set up from the soil water to the cell sap, and the cell thus absorbs 
water containing the necessary mineral food. This process, then, is not peculiar 
to living organisms. In a like manner, the chemist looks upon the synthesis of 
carbohydrates in the plant as a purely chemical process. While this process has 
not been reproduced in all its steps by the chemist, yet he, with the botanist, 
looks upon this as a process which can be carried on independently of the plant. 
Now let us examine one or two cases of ecological phenomena. Certain leaves 
when exposed to too much light twist on their petioles so as to bring the edge of 
the leaf in the direction of the light; that is, the leaf lies in the plane of the in- 
cident rays. They thus escape the injurious effects of the light, and, what is 
more important, at the same time escape the accompanying heat rays, and thus 
reduce the evaporation from the leaf surface. This phenomenon, known as ‘*‘ para- 
heliotropism,’’ is common in plants of the dry regions. The organ in this case 
responds to a stimulus, and responds in such a way as to protect itself against in- 
jury. A plant under these circumstances is said to adapt itself to its environ- 
ment. A phenomenon of this kind is more distinctly vital. I do not wish to be 
interpreted as separating vital phenomena as fundamentally different from non- 
vital. From a philosophical standpoint, I cannot admit that they are; but on 
account of the extreme complexity of the combinations they are more con- 
veniently studied as combinations. No doubt the phenomena of paraheliotropism 
is capable of analysis and will be found to be a combination of so-called single 
phenomena. But it is really this adaptibility or mobility in a plant which dis- 
tinguishes a living thing from a piece of apparatus. 
It is not my intention to discuss the fundamental relations of ecology to phys- 
ics and chemistry, nor to propound a theory of life. Instead I wish to give a 
brief outline of the subject in its present status. I interpret this as the wish of 
the Academy when the subject was assigned to me. 
During the Linnzan period, and for some time afterward, plants were studied 
only to be classified. As you all know, the nature philosophy of that day looked 
upon species as fixed; hence, the chief care of the botanist was to so describe a 
plant that it could with certainty be distributed into its proper pigeonhole. 
The descriptions in Linnzeus’s ‘‘Species Plantarum’”’ are models of clearness. The 
pigeonholes are well distinguished. But, alas! the plants so often fail to con- 
form to the descriptions. When considering two closely allied species Linnzus 
apparently threw into the waste-basket all intermediate forms. Botanists in 
general seem not to have taken much interest in plants as living organisms. 
This tendency persists more or less to the present day, but is fast disappearing. 
Systematic botany holds a prominent position in the various branches of the 
botanical science; but its study is modified to suit the accepted philosophy of de- 
velopment. 
One of the earliest to record systematic observations in ecology was Sprengel, 
who in 1793 published a little book upon ‘The Secret of Nature in the Form and 
Fertilization of Flowers Discovered.’’ He laid the foundation of the theory of 
honey containing flowers, viz.: that the flower secretes nectar to attract insects, 
sometimes a single species; that the flower is of such a shape that the insect in 
getting the nectar is compelled to transfer, unconsciously of course, the pollen 
from the anthers to the stigma. It is a curious fact, however, that Sprengel did 
not recognize the real reason for all this: that the insects were utilized by the 
plant to transfer pollen from one plant to another because cross-fertilization is 
better for the plant than self-fertilization. The result was that Sprengel’s ex- 
