Atavism 23 



ually gain in strength, until they finally reach the stage 

 necessary to make them visible. Here again it must there- 

 fore be assumed that every hereditary character is misci- 

 ble to any extent with the others. 



The independence of the hereditary characters is most 

 beautifully shown in atavism. A character may remain 

 latent through a number of generations while all the 

 others unfold normally. From time to time it appears 

 again, mostly without exercising any kind of influence on 

 the other characters. We do not know what external 

 circumstances condition this reappearance; in all prob- 

 ability they do not act simply on the atavistic individuals, . 

 but we must conceive that the given potentiality is alway^ 

 latent in the others, only it is very fluctuating in its 

 strength. To us only the crests of the highest waves are 

 visible. 



To all appearance such qualities can be transmitted 

 through a long series of generations, from one generation 

 to another. Their existence can be reckoned by millen- 

 niums in those cases where they are at least as old as the 

 species itself. I mean the cases of reversion to the ances- 

 tors of the species, of which the zebra-like stripes of the 

 horse form such a well-known instance. 9 We have a 

 similar illustration in the Primula acaulis var. caulescens, 

 which occurs from time to time in the field as a quite 

 isolated specimen among thousands of non-umbellate 

 plants, and then forms an inflorescence quite similar to 

 that of the most nearly allied umbellate species. Culti- 

 vation has taken possession of this more richly flowering 

 variety, and has put it on the market in many nuances of 

 color. 



I should not close this section without having pointed 



9 Darwin, Joe. cit, 1: 59. 



