Page:Popular Science Monthly Volume 67.djvu/63

Rh 5. That the process of selection of individual fluctuations can, at best, only keep the species up to an artificial standard that will be lost as soon as a rigorous process of selection ceases, has been shown by de Vries and others. The permanent inheritance of each species can not have been acquired in this way. Unless, for example, those individuals whose life is somewhat longer or shorter were being constantly destroyed in every generation the little would soon be lost that had been so laboriously gained. It is needless to point out that no such process is taking place on a scale sufficient to regulate the evolutionary process.

6. The length of life of a species is something that is as characteristic of the species as any of its structural or physiological properties. To state that the duration of life can not be supposed to be the result of physiological processes is not simply paradoxical but absurd. The paradox and also the absurdity disappear as soon as we recognize the fact that the length of life is a characteristic of each new species and is a purely physiological process. Those new elementary species whose physiological processes fulfill the conditions of a certain environment survive, those that do not perish; and there is no subsequent lengthening of one character and shortening of another, as on a sliding scale, to fit the new form in all details to its new environment. The length of life is predetermined with the advent of the new form, and is not subsequently regulated for the benefit of that particular species. From this point of view we get a simple and clear analysis of the problem, while that which Weismann maintains leads only to an unmeaning 'paradox.'

It seems to me that the method of the Darwinian school of looking upon each particular function, or structure, of the individual as capable of indefinite control through selection is fundamentally wrong. For instance, in regard to the number of eggs characteristic of each species, it is assumed that the output is also regulated by means of selection. On the contrary it appears to me that the power to produce a certain number of eggs is one of the fixed characteristics of each species that appears, and is not increased or diminished by external needs. The number of individuals that reach maturity will stand, therefore, as a measure of how far a new species is from the beginning adapted to the old environment, or to the new one in which it establishes itself. There may be a wide range of perfection in this respect, for there are some species that produce few eggs, but succeed in bringing a large number of them to maturity, and there are other species which, despite the countless number of eggs that they produce, only succeed in barely holding on to existence. Since the great majority of lower animals and plants produce large numbers of eggs we may infer that the arrangement for propagation, while it suffices to keep the species in