[From introduction:]
For a number of years the writer has endeavored to assemble material from the older faunas which might illuminate the incipient expressions of dependent life. It is through this avenue only that the problem of the origin of the symbiotic conditions which now pervade all nature can ultimately be approached with hope of resolution.
The dependent condition of individual existence is one of the manifold presentments of organic adaptation which is to be comprehended best by comparison of the complicated conditions prevalent today with their simpler expressions in the early life of the earth. Adaptation is in large measure a sociological problem of immediate concern. It is not proper to consider the more serious features of sociological adaptation as merely analogous to organic adaptation. In human society dependence means simplicity, that is, loss of complexity; it reduces moral independence and induces idleness, beggary, misery and crime. Here is no question of analogy, but rather of continuity of mode, of cause and effect, penetrating human society. Such laws as govern its fundamental and primary manifestations are to be sought in the primitive life of the earth.
I am fully aware of what extensive data are essential to adequate conclusions in this inquiry and how far-reaching the bearings of the inquiry must be. At this time I should go no further perhaps than to point out some of the very numerous and most instructive expressions of these conditions which it has been practicable to bring together, abiding in the hope of eventually collating more copious data. I shall not go too far, however, in suggesting certain obvious inferences which seem entirely justified by these data and by the general principles of adaptation.