On Germinal Selection as a Source of Definite Variation

30

If any one should deem these words too severe, let him read the sarcastic passages in which Eimer has dispatched the late unfortunate Eric Haase who had been presumptuous enough to oppose the Tübingen Professor's deliverances on certain points. Haase, as we all know, fell a victim to the climate of the tropics, shortly after resigning the post of Director of the natural science collections in Bangkok, in order to return to Germany and to work out the fruits of his tropical sojourn. The unfortunate end of this accomplished man who had rendered important services to science had no effect in mollifying the resentment of Herr Eimer at the opposition which his views had encountered; and in twenty printed pages he takes him to task in the most personal and rancorous manner for this affront, remarking at the close: "In the meantime Herr Haase has died. Nevertheless I owe it to myself, in spite of this occurrence, to make public the foregoing facts, in order," etc. Any one who is interested in knowing the motives of Herr Eimer's excuse may find them in his book Artbildung and Verwandtschaft bei den Schmetterlingen, Part II., p. 66.

31

"Gedanken zur Descendenz- und Vererbungstheorie." Biolog. Centralblatt, July 15, 1893.

32

C. Lloyd Morgan, Animal Life and Intelligence, London, 1890-1891, p. 30-33.

33

On the same day on which the present address was delivered at the International Congress of Zoölogists in Leyden, and on the same occasion, Dr. W. B. Scott, Professor of Geology in Princeton College, New Jersey, read a very interesting paper on the tertiary mammalian fauna of North America, in which, without a knowledge of my paper, he took his stand precisely on this argument and arrived at the opinion that it could not possibly be the ordinary individual variations which accomplished phyletic evolution, but that it was necessary to assume in addition phyletic variations. I believe our views are not as widely remote as might be supposed. Of course, I see no reason for assuming two kinds of hereditary variations, different in origin. Still it is likely that only a relatively small portion of the numberless individual variations lie on the path of phyletic advancement and so under the guidance of germinal selection mark out the way of further development; and hence it would be quite possible in this sense to distinguish continuous, definitely directed individual variations from such as fluctuate hither and thither with no uniformity in the course of generations. The root of the two is of course the same, and they admit of being distinguished from each other only by their success, phyletic modification, or by their failure.

34

Delâge, in La structure du protoplasma et les théories sur l'hérédité, etc., Paris, 1895, is mistaken in attributing to Herbert Spencer the merit of having first pointed out the necessity of the assumption of biological units ranking between the molecule and the cell. Brücke set forth this idea three years previously to Spencer and established it exhaustively in a paper which in Germany at least is famous ("Elementarorganismen," Wiener Sitzungsberichte, October 10, 1861, Vol. XLIV., II., p. 381). Spencer's Principles of Biology appeared between 1864 and 1868; consequently there can be no dispute touching the priority of the idea. Strangely enough Delâge cites Brücke's essay in the Bibliographical Index at the end of his book correctly, although Brücke's name and views are nowhere mentioned in the book itself. It is to be observed, however, that the elementary organisms of Brücke are not merely the precursors of Spencer's "physiological units," but repose on much firmer foundations than the latter, which, as Delâge himself remarks, are at bottom nothing more than magnified molecules and not combinations of different molecules of such character as to produce necessarily phenomena of life. He aptly remarks on this point: "the physiological units of Spencer are only chemical molecules of greater complexity than the rest, and as he defines them they would be regarded as such by every chemist. He attributes to them no property essentially different from those of chemical molecules." Assimilation, growth, propagation, in short the attributes of life, are not attributed by Spencer to his units, while Brücke by his very designation "elementary organisms" expresses the idea of "ultimate living units," to use Wiesner's phrase. Of course this particular aspect of the vital units was not emphasised by Brücke with the same distinctness and sharpness as by recent inquirers, who took up Brücke's ideas thirty years after. I refer to the conception that the union of a definite combination of heterogeneous molecules into an invisibly small unit, forms the cradle or focus of the vital phenomena. This was first done and apparently on independent considerations by De Vries, and soon after by Wiesner, and subsequently by myself (De Vries, Intracelluläre Pangenesis, Jena, 1889; Wiesner, Die Elementarstructur and das Wachsthum der lebenden Substanz, Vienna, 1892; Weismann, Das Keimplasma, Jena, 1892). Let me say at the close of this note that it is not my intention in thus defending the rights of a great physiologist, to censure in the least the distinguished author of L'hérédité who has set himself a remarkably high standard of exactitude in such matters. Certainly, when we consider the enormous extent of the literature that had to be mastered to produce his book, embracing as it did all the various theories of recent times, such an oversight is quite excusable.

35

Materials for the Study of Variation with Especial Regard to Discontinuity in the Origin of Species, London, 1895, p. 16.

36

"Gedanken zur Descendenz- and Vererbungstheorie," Biolog. Centralblatt, 1893, Vol. XIII., p. 397.