1 8 Heredity, Variation and Genius 



even sometimes into another so-called species, for 

 intermediates often bridge the gaps between 

 species and confound distinctions. A not entirely 

 strange event, if it happen, seeing that when a 

 common human stock gives birth to an uncommon 

 genius nature does make a very palpable leap, 

 progressing then by multiple proportion rather 

 than by continuous addition. The individual 

 mortal, like the individual plant or animal, bursts 

 the formidable fetters of custom, always so 

 mightily potent to make men what they are, and 

 to keep them as they are and as for the most part 

 they like to be. 



The conjecture may perhaps exact support 

 from the diligent observations of the eminent 

 Dutch botanist De Vries on a long series of 

 breedings and crossings of plants. The results 

 of his numerous and industrious experiments have 

 fully convinced him that the ordinary continuous 

 variations occurring normally, on which Darwin 

 supposed natural selection to work, are merely 

 indefinite fluctuations due to light, soil, space, 

 climate, moisture and the like conditions, and 

 take no part in the origin of species ; although 

 they are of the nature of acquired characters and 

 capable of hereditary transmission they are not 

 naturally selected to make new starts of evolution. 

 On a multitude of careful observations he has 

 based a theory of so-called mutations which is 

 gaining large acceptance in biology — the theory 

 that definite co-ordinate variations of discon- 



