Another cause of the numerical abundance of life exists, as already stated, in the conditions of nourishment.  Energy is more readily conveyed to the various parts of the smaller mass, and hence the lesser organisms will more actively functionate; and this, as being the urging dynamic attitude, as well as that most generally favourable in the struggle, will multiply and favour such forms of life.  On the other hand, however, these forms will have less resource within themselves, and less power of endurance, so that they are only suitable to fairly uniform conditions of supply; they cannot survive the long continued want of winter, and so we have the seasonal abundance of summer.  Only the larger and more resistant organisms, whether animal or vegetable, will, in general, populate the Earth from year to year.  From this we may conclude that, but for the seasonal energy-tides, the development of life upon the globe had gone along very different lines from those actually followed.  It is, indeed, possible that the evolution of the larger organisms would not have occurred; there would have been no vacant place for their development, and a being so endowed as Man could hardly

[1] Weismann, The Duration of Life.

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have been evolved.  We may, too, apply this reasoning elsewhere, and regard as highly probable, that in worlds which are without seasonal influences, the higher developments of life have not appeared; except they have been evolved under other conditions, when they might for a period persist.  We have, indeed, only to picture to ourselves what the consequence of a continuance of summer would be on insect life to arrive at an idea of the antagonistic influences obtaining in such worlds to the survival of larger organisms.

It appears that to the dynamic attitude of life in the first place, and secondarily to the environmental conditions limiting undifferentiated growth, as well as to the action of heredity in transmitting the reproductive qualities of the parent to the offspring, the multitudes of the pines, and the hosts of ants, are to be ascribed.  Other causes are very certainly at work, but these, I think, must remain primary causes.

We well know that the abundance of the ants and pines is not a tithe of the abundance around us visible and invisible.  It is a vain endeavour to realise the countless numbers of our fellow-citizens upon the Earth; but, for our purpose, the restless ants, and the pines solemnly quiet in the sunshine, have served as types of animate things.  In the pine the gates of the organic have been thrown open that the vivifying river of energy may flow in.  The ants and the butterflies sip for a brief moment of its waters, and again vanish into the

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inorganic:  life, love and death encompassed in a day.