Miscellaneous Papers. 161 



throughout nature, as regards the struggle for existence, indicate a 

 compromise of individuals bound by a fundamental law of altru- 

 ism, which is operative everywhere. These views are striking and 

 impressive, and illustrate the idea that the evolution discussion 

 has been stimulating to originality of thought. 



Darwin has been much criticized for his theories of heredity, 

 and yet, as in other branches of biology, his ideas revolutionized 

 this branch and gave thought upon the subject a new trend. For 

 instance, his theory of pangenesis has been condemned as exploded, 

 and yet Weisman's theory of germ plasm is along the same lines 

 , and furnishes explanations that nothing else can give. Darwin's 

 theory of pangenesis he explains as meaning (Var. Domes., II, p. 

 350), "that every separate part of the whole organization repro- 

 duces itself. So that ovules, spermatazoa and pollen grains — the 

 fertilized seed, as well as buds — include and consist of a multitude 

 of germs thrown off from each separate part or unit. . . . (P. 

 378:) According to our hypothesis all forms of reproduction de- 

 pend upon the aggregation of gem mules derived from the whole 

 body." The power of growth and development, as well as the re- 

 pair and reproduction of injured aod lost parts, especially in lower 

 animals, is fully explained, he contends, by assuming the presence 

 of the gemmules in all parts of the body with particular affinities and 

 tendencies. (P. 397:) "The chief assumption is," he says, "that 

 all the units of the body, besides having the universally admitted 

 power of self-division, throw off minute gemmules that are dis- 

 persed through the system. ... In a highly organized animal 

 the gemmules thrown off from each unit of the body must be incon- 

 ceivably numerous and minute. Each unit of each part, as it 

 clianges during development, must throw off its gemmules. (P. 

 398:) The units of the body are generally admitted by physiolo- 

 gists to be autonomous. I go one step further and assume that 

 they throw off reproductive gemmules. Thus an organism does 

 not generate its kind as a whole, but each separate unit generates 

 its kind. . . . Inheritance must be looked at as merely a form 

 of growth, like the self-division of lowly organized unicellular or- 

 ganisms." From this lucid statement of his theory, and the logic 

 of it, we cannot wonder that the theories of heredity were com- 

 pletely revolutionized by the promulgation of what he calls his 

 provisional hypothesis. 



Following De Vries's principle, and next in importance, was 

 Mendelism — the idea of mathematical proportions in the inherited 

 and transmissible qualities of plants and animals. It was the dis- 

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