Evolution Social and Organic

by Arthur M. Lewis

But although this controversy has split the evolutionists into two camps, it in no way compromises the evolution theory itself. The controversy is based on the admission of all the parties to it, that evolution is granted, and the question at issue involves only a difference as to how the acknowledged results are accomplished. Evolution is no longer merely a theory, it is an established fact, and is recognized as such by all who live in an intellectual atmosphere belonging to this side of 1859, the year of the publication of the “Origin of Species.”

Neither does the result of this discussion threaten, in any way, the validity of the Darwinian theory of “Natural Selection.” All the disputants are avowed Darwinians, and disagree only as to whether Darwin’s theory is alone sufficient to account for the origin of new species.

Professor Packard, Lamarck’s biographer, and one of his warmest admirers, at the close of his chapter devoted to the denial of “pure” Darwinism says: “We must never forget or under-estimate, however, the inestimable value of the services rendered by Darwin, who by his patience, industry, and rare genius for observation and experiment, and his powers of lucid exposition, convinced the world of the truth of evolution, with the result that it has transformed the philosophy of our day. We are all evolutionists, though we may differ as to the nature of the efficient causes.”

There are now three possible positions. (1) That of the Lamarckians, pure and simple, who maintain that Lamarck’s theory in itself explains all the phenomena, and that Darwin’s principle of selection is not only invalid but superfluous. This school is practically extinct, though Packard often sails to its very edge in his efforts to defend his subject, as is the manner of biographers. (2) The Neo- (New)-Lamarckians who develop Lamarck’s theory and add to it Darwin’s selective principle as of greater, equal, or secondary importance, according as they lean the more strongly to Darwin or Lamarck. This position held the field almost alone, until Weismann fired his opening gun in 1883. He founded (3) the Neo-Darwinian school which repudiates altogether the Lamarckian factor of the hereditary transmission of acquired characters, and maintains that Darwin’s theory is able to dispense with Lamarckian ideas of use and disuse.

As Weismann is the storm center of the controversy we will now examine his theory.

In 1883 Weismann became the pro-Rector of the University of Freiburg and in the hall of the University, in June of that year, he publicly delivered his inaugural lecture “On Heredity.” This lecture is generally regarded as the first broadside in that war which filled with its reverberations the scientific magazines of the world for the next thirteen years. As one writer aptly says, “The warring scientists splashed like irate cuttle-fishes in clouds of their own ink.” About 1896 however, the public grew tired of the never-ending flood of biological lore on what looked to the lay mind like an insoluble problem. The editors, with their fingers on the public pulse, cried, “A plague on both your houses,” and sent the savants to seek in their laboratories the victories denied to their pens.

As a matter of fact however, the coming struggle was foreshadowed in a paper read by Weismann at the meeting of the Association of the German Naturalists at Salzburg, two years earlier, in 1881.

This paper was entitled “The Duration of Life,” and the subject was still further developed in an academic lecture, in 1883, on “Life and Death.” These two biological contributions not only indicated the foundations of Weismann’s theory, but they threw a very brilliant light in certain very dark places. Weismann not only took up, but he solved the hitherto obscure question of the origin of death.

Johannes Muller had, as early as 1840, rejected the prevailing hypothesis which held the death of animals to be due to “the influences of the organic environment, which gradually wear away the life of the individual.” Muller argued that if this were so “the organic energy of an individual would steadily decrease from the beginning.” Everybody knows, however, that in spite of the wear and tear caused by the “environment,” be it organic or inorganic, the volume of life increases, until a certain stage is reached in all animals. But Muller had failed to fill the gap his criticism had created.

This problem Weismann solved by analysing the methods of reproduction among animals. These generally speaking are two; sexual, and non-sexual or, as it is sometimes termed, a-sexual. This latter form is the mode that prevails at the bottom of the organic scale—among the protozoa, animals consisting of a single cell. This method has a variety of forms which are classified by Haeckel as (1) self-division; (2) formation of buds; (3) the formation of germ-cells or spores. We shall here deal only with the first, self-division, or fission, which is the most universal of all methods of propagation, being the progress by which the individual cells which compose all the higher animals multiply themselves. This is the method vital to Weismann’s theory and the other two are no more than distinct modifications of fission.