motions. And thus possibly the conditions then
obtaining involved a progressively increasing complexity of
material structure the genesis of the elements, from an
infra-hydrogen possessing the simplest material configuration,
resulting ultimately in such self-luminous nebula as we yet see
in the heavens.

The late James Croll, in his _Stellar Evolution_, finds objections
to an eternal evolution, one of which is similar to the
"metaphysical" objection urged in this paper. His way out of the
difficulty is in the speculation that our stellar system
originated by the collision of two masses endowed with relative
motion, eternal in past duration, their meeting ushering in the
dawn of evolution. However, the state of aggregation here
assumed, from the known laws of matter and from analogy, calls
for explanation as probably the result of prior diffusion, when,
of course, the difficulty is only put back, not set at rest. Nor
do I think the primitive collision in harmony with the number of
relatively stationary nebula visible in space.

The metaphysical objection is, I find, also urged by George
Salmon, late Provost of Trinity College, in favour of the
creation of the universe.--(_Sermons on Agnosticism_.)

A. Winchell, in _World Life_, says: "We have not

301

the slightest scientific grounds for assuming that matter existed
in a certain condition from all eternity. The essential activity
of the powers ascribed to it forbids the thought; for all that we
know, and, indeed, as the _conclusion_ from all that we know,
primal matter began its progressive changes on the morning of its
existence."

Finally, in reference to the hypothesis of a unique determination
of matter after eternal duration in the past, it may not be out
of place to remind the reader of the complexity which modern
research ascribes to the structure of the atom.

302

INDEX

A.

Abney, Sir Wm., on sensitisers, 210.

Abundance of life, numerical, 98-100.

Adaptation and aggressiveness of the organism, 80.

Additive law, the, with reference to alpha rays, 220.

Age of Earth, comparison of denudative and radioactive methods of
finding, 23-29.

Aletsch glacier, 286.

Allen, Grant, on colour of Alpine plants, 104.

Allen, H. Stanley, on photo-electricity, 203.

Alpha rays, nature of, 214; velocity of, 214; effects of, on
gases, 214; range of, in air, 215; visualised, 218; ionisation
curve of, 216; number of, from one gram of radium, 237; nu