We owe our modern ideas of such variations mainly to de Vries and to those who have followed in his footsteps. Such sudden changes have been long known and were spoken of by Darwin as saltations—or sports. Darwin knew of cases like the ancon ram, from which a race of shortlegged sheep was produced. He knew that totally black or melanistic mutations and albinos arise in many groups suddenly, and transmit their characters. A black-shouldered or japanned peacock has appeared more than once and perpetuated itself without selection. It would be out of place to-day to discuss this absorbing problem. That extreme mutations may at times have been an element of progress in nature few will deny, especially if we exclude such monstrous forms as those the breeder has used in building up domesticated races of animals.
It is not, however, to these extreme examples of definite variations that I wish especially to draw your attention, but to that group of smaller variations of a similar nature that may at their first appearance fall within the limits of ordinary variability. I now ask you, therefore, to follow me in an attempt to apply this latest discovery to the theory of evolution.
If we trace the ancestors of any living animal—man, for example—we discover that his ancestry goes back not as a single line, nor as a converging system of lines, but as a vast branching network. Each man has had 2 parents, 4 grandparents, 8 great-grandparents, 16 in the fourth generation, 32 in the fifth, 64 in the sixth, 128 in the seventh, 256 in the eighth, 512 in the ninth, 1,024 in the tenth. A few generations further removed we should expect to find that the majority of all the individuals of the species had poured their blood, as we say, into each individual of the future generations. Each of us is the descendant of a large population. The statement is not strictly true, for some lines die out, many lines cross, and caste has narrowed the field, but the statement suffices to show that a species moves along as a horde rather than as the offspring of a few individuals in each generation. The mass serves to keep the species afloat in times of calamity, it may have little else to do directly with its advance. Nevertheless this fundamental fact is too often overlooked in the attempt to explain the origin of new races, varieties and species from single favorable variations.
For advance we must look to those individuals that contribute something new to the species—it is the superman that will add something to the common level of humanity, but the rest keep the race alive until his advent and then carry his kind forward on an advancing wave.
If we could count those individuals that are the pioneers of advance, their number might be very small; in order to survive, they must graft themselves onto the stock. They are the harbingers of the better times to come—the forerunners of progress.