Page:Popular Science Monthly Volume 74.djvu/339

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335
LIFE AND WORKS OF DARWIN

There is some lack of perspective, some egotism, much one-sidedness in modern criticism. The very announcement, "Darwin deposed," attracts such attention as would the notice "Mt. Blanc removed"; does it not argue courage to attack a lion even when deceased? Preoccupation in the study of one great law, as in the case of Bateson on Mendelism and De Vries on Mutation blinds to every other law. To be dispassionate, let us remember that Darwin's hypothesis was framed in 1838, seventy years ago. Are the two great Cambridge men, Newton and Darwin, lesser men because astronomy and biology are progressive sciences? Secondly, to know your Darwin you must not judge him by single passages but by all he wrote. Darwin is not to be known through the extremes of those of his followers with whom an hypothesis has become a creed. Heading him afresh and through and through we discover that his "variation" and "variability" are very broad and elastic terms. Every actual example he cites of his main hypothesis, such as the speed of the wolf, or the deer, or the long neck of the giraffe, is a variation both heritable and of adaptive value.

"When we put together all the concrete cases which he gave to illustrate his views of selection we see that he includes both continuous and discontinuous variations, both the shades of difference of kind and proportion and the little leaps or saltations from character to character. For example, certain cases of immunity to disease are now known to be "unit characters" in Bateson's sense, or "mutants" in the De Vries sense. Darwin repeatedly referred to immunity as a variation which would be preserved by selection. Moreover, Darwin's own repeated assertion of his profound ignorance of the laws of variation certainly pointed the way to the investigation of these laws, and it is this very study which is modifying the applications of his selection hypothesis.

From first to last Huxley maintained that it would require many years of study before naturalists could say whether Darwin had been led to overestimate the power of natural selection. Darwin's mind from first to last was also open on this point. Through every edition of the "Origin" we find the passage:

The laws governing the incipient or primordial variations (unimportant except as the groundwork for selection to act on and then all important) 1 shall discuss under several heads. But I can come, as you may well believe, to only very partial and imperfect conclusions.

In 1869 and in the latest edition of the "Origin" Darwin speaks of "individual differences" as of paramount importance, but he illustrates these differences by such instances as the selection of passenger pigeons with more powerful wings, or the selection of the lightest colored birds in deserts.