that local accumulation of wrinkling which we term mountain
chains. The

[1] Bull. Geol. Soc. America, vol. xxvi, March 1915.

xii

paper on _Alpine Structure_ is a reprint from "Radioactivity and
Geology," which for the sake of completeness is here included. It
is directed to the elucidation of a detail of mountain genesis: a
detail which enters into recent theories of Alpine development.
The weakness of the theory of the "horst" is manifest, however,
in many of its other applications; if not, indeed, in all.

The foregoing essays on the physical influences affecting the
surface features of the Earth are accompanied by one entitled _The
Abundance of Life._ This originated amidst the overwhelming
presentation of life which confronts us in the Swiss Alps. The
subject is sufficiently inspiring. Can no fundamental reason be
given for the urgency and aggressiveness of life? Vitality is an
ever-extending phenomenon. It is plain that the great principles
which have been enunciated in explanation of the origin of
species do not really touch the problem. In the essay--which is an
early one (1890)--the explanation of the whole great matter is
sought--and as I believe found--in the attitude of the organism
towards energy external to it; an attitude which results in its
evasion of the retardative and dissipatory effects which prevail
in lifeless dynamic systems of all kinds.

_Other Minds than Ours_? attempts a solution of the vexed question