A COMPARISON BETWEEN ARTIFICIAL AND NATURAL 



SELECTION 



Br HUGO DE VRIES 



[Hugo de Vries, Professor of Botany, University of Amsterdam since 1878. b. 

 Haarlem, Holland, 1848. Phil. Nat. Doct. University of Leyden, 1870; Sc.D. 

 Columbia University; LL.D. University of Chicago, Jacksonville College; 

 Postgraduate, Heidelberg, 1870-71; Wiirzburg, 1871-72; Privat-docent, Halle, 

 1877; Lecturer in Mutation Theory, University of California, 1904; Member of 

 the Academy of Sciences, Amsterdam; National Academy of Sciences, Wash- 

 ington; American Philosophical Society, Philadelphia; Royal Society, London; 

 Honorary Member of the Academies of Sciences of New York and of California, 

 San Francisco; Corresponding Member of the Academies of Copenhagen, Brus- 

 sels, Rome, Regensburg, Upsala, Miinchen, Philadelphia, Christiania; Honorary 

 Member of the Deutsche Botanische Gesellschaft, Berlin, etc. Author of Intra- 

 cellulare Pangenesis; Die Mutations-Theorie; Species and Varieties, Their Ori- 

 gin by Mutation.] 



NATURAL selection, as pointed out by Darwin, is one of the great 

 principles which rule the evolution of organisms. It is the sifting out 

 of all those of minor worth, through the struggle for life. It is only 

 a sieve, and no force of nature, no direct cause of improvement, as 

 has so often been asserted. Its only function is to decide what is to 

 live and what is to die. Evolutionary lines, however, are of long 

 extent, and everywhere many side-paths are occurring. It is the 

 sieve that keeps evolution on the main lines, killing all or nearly all 

 that try to go in other directions. By this means natural selection is 

 the one great cause of the broad lines of evolution. 



With the single steps of that evolution, of course, it has nothing 

 to do. Only after the step has been taken, the sieve decides, throw- 

 ing out the bad, and thereby enabling the good to produce a richer 

 progeny. The problem how the individual steps are brought about, 

 is quite another side of the question. 



On this point Darwin has recognized two possibilities. One means 

 of change lies in the sudden and spontaneous production of new 

 forms from the old stock. The other method is the gradual accumu- 

 lation of the always present and ever-fluctuating variations. The 

 first changes are what we now call mutations, the second are desig- 

 nated individual variations, or, since this term is often used in 

 another sense, as fluctuations. Darwin recognized both lines of 

 evolution, but his followers have propounded the exclusive part of 

 the latter processes. 



To my conviction the current scientific belief is wrong on this 

 point. Horticultural experience and systematic inquiry seem to 

 point in exactly the opposite direction. The evidence collected of late 

 by Korshinsky from horticultural practice, may be regarded as inade- 

 quate for a full proof, most of the single cases being surrounded by 



