{Fig. 4}

the changes progressing—­let us say, in the solar system, or in the process of a crystallisation, would appear as lines sloping downwards from left to right.

Whatever our views on the origin of death may be, we have to recognise a periodicity of functions in the life-history of the successive individuals of the present day; and whether or not we trace this directly or indirectly to

90

a sort of interference with the rising wave of life, imposed by the activity of a series of derived units, each seeking energy, and in virtue of its adaptation each being more fitted to obtain it than its predecessor, or even leave the idea of interference out of account altogether in the origination or perpetuation of death, the truth of the diagram (Fig. 4) holds in so far as it may be supposed to graphically represent the dynamic history of the individual.  The point chosen on the curve for the origination of a derived unit is only applicable to certain organisms, many reproducing at the very close of life.  A chain of units are supposed here represented.[1]

THE LENGTH OF LIFE

If we lay out waves as above to a common scale of time for different species, the difference of longevity is shown in the greater or less number of vibrations executed in a given time, i.e. in greater or less “frequency.”  We cannot indeed draw the curvature correctly, for this would necessitate a knowledge which we have not of the activity of the organism at different periods of its life-history, and so neither can we plot the direction of the organic line of propagation with respect to the

[1] Projecting upon the axes of time and energy any one complete vibration, as in Fig. 4, the total energy consumed by the organism during life is the length E on the axis of energy, and its period of life is the length T on the time-axis.  The mean activity is the quotient E/T.

91

axes of reference as this involves a knowledge of the mean activity.[1]

The group of curves which follow, relating to typical animals possessing very different activities (Fig. 5), are therefore entirely diagrammatic, except in respect to the approximate

{Fig. 5}

longevity of the organisms. (1) might represent an animal of the length of life and of the activity of Man; (2), on the same scale of longevity,

[1] In the relative food-supply at various periods of life the curvature is approximately determinable.

92

one of the smaller mammals; and (3), the life-history of a cold blooded animal living to a great age; e.g. certain of the reptilia.