must become adapted. "Two canine animals in a time of dearth," he remarks, "may truly be said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture."[1] Also, "climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought seem to be the most effective of all checks."[2] Yet further, "when we reach the Arctic regions, or snow capped summits, or absolute deserts, the struggle for life is almost exclusively with the elements."[3] Again, Mr. Darwin often means, not a struggle for food or against the elements, but a struggle to avoid being converted into food. "Very frequently," he writes, "it is not the obtaining of food, but the serving as prey to other animals, which determines the average numbers of a species."[4] And some of his most fascinating pages deal with the variations, such as protective markings, colorings and habits, which are helpful in the mere struggle for safety. Once more, in those paragraphs in "The Descent of Man" already referred to, in which Mr. Darwin recognizes the utility of group solidarity, he, by implication, takes account of a struggle on the part of associating individuals to adjust their interests and their activities to one another in such wise that group life may be maintained.
If, then, it is legitimate to use the term, "struggle for existence," "in a large and metaphorical sense," as Mr. Darwin says his practise is,[5] the struggle itself obviously consists of four distinct and specific struggles, namely: (1) the struggle for safety; (2) the struggle for subsistence; (3) the struggle for adaptation by every organism to the objective conditions of its life, and, (4) the struggle for adjustment, by group-living individuals to one another.
And this large use of the term is legitimate in fact. Mr. Darwin's only mistake was in calling it "metaphorical." For, as Karl Pearson has pointed out, "the true measure of natural selection is a selective death rate,"[6] and any circumstance, whether it be danger, or scarcity of food, or non-adaptation to physical conditions, or mal-adjustment of associating individuals to one another, which affects the selective death rate, is a factor in the struggle for existence.
If so much be granted, a number of difficult questions get a real illumination. What are the true relations of esthetic and economic, of ethical and social phenomena to one another, and to life in its wide inclusiveness? What, especially, is the precise point of departure of
