and other descent series entirely unknown in Darwin's time certainly prove beyond question that law rather than chance is prevailing in variation.
What the nature of these laws is it is still too early to say. Personally I am strongly of the opinion that the laws of life, like the ultimate laws of physics, may ultimately prove to be beyond analysis.
To allow myself just one flight of fanciful statement drawn from personal observation and reflection I may say there is a likeness between the unit forces working in a single organism, both as revealed by the microscope and in fossil series, and the individual soldiers composing a giant army. The millions of well-ordered activities in the body correspond with the millions of intelligently trained men who compose the army; the selection process or the survival of the fittest is like the competition between two armies, between the Russian and Japanese, for example. It is an outward and visible competition between two internally prepared and well-ordered hosts of units and groups of units. Selection is continuously working upon the army as a whole and also upon every unit which affects survival—an immunity unit, an intelligence unit, a speed unit, a color or group of color units; just as in the army it is working upon units of courage, of strategy, of precision of fire, of endurance, of mass. In this sense it is perfectly true to say with Darwin "that selection works upon certain single variations." It is not true or at least it is not shown, that these variations are a matter of chance; they rather appear to be a matter of law as indeed Darwin foresaw when he stated that he used the word "chance" merely as a synonym of "ignorance."
In the present state of biology we are studying the behavior of the thousands of parts, sometimes of blending, sometimes of separate, sometimes of paired or triplicate units, which compose the whole and make up the individual organism. Natural selection determines which organism shall win; more than this, it determines which serviceable activities of each organism shall win. Here lie the limits of its power. Selection is not a creative principle, it is a Judicial principle. It is one of Darwin's many triumphs that he positively demonstrated that this judicial principle is one of the great factors of evolution. Then he clearly set our task before us in pointing out that the unknown lies in the laws of variation and a stupendous task it is. At the same time he left us a legacy in his inductive and experimental methods by which we may blaze our trail.
Therefore, in this anniversary year, we do not see any decline in the force of Darwinism but rather a renewed stimulus to progressive search. As Huxley says: