David Starr Jordan 



ancestral states are brought about by good soil; 

 sometimes (perhaps oftener), also, by starvation; 

 new variations oftenest by rich soil and general 

 prosperity. There is no evidence of any limit in the 

 production of variation through artificial selection^ 

 especially if preceded by crossing. Mutations are 

 probably due to the sudden appearance of latent 

 tendencies in new combinations, producing novel 

 effects analogous to new chemical combinations/' 



' ' Mutation is not a period, but a state induced by 

 various hereditary and external conditions. It is 

 not by any means certain that there is any period 

 in the life-history of the species when it is more 

 subject to mutation than at other times, other 

 conditions being similar. By crossing different 

 species we can form more variations and muta- 

 tions in half-a-dozen generations than will be 

 developed by ordinary variation in a hundred or 

 even a thousand generations." 



* ' The La France and some other roses, as well 

 as dahlias, calks and many other plants, every 

 once in a while throw out, on some particular 



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