ii.] RESPONSE TO ENVIRONMENT 19 



basis of response to environment to be either 

 due to some more marked influence of substances 

 in the soil or of "crossing," or of the accumula- 

 tion of effects lying dormant till the marked 

 changes suddenly appear in an offspring. That 

 " recessive " characters may be dormant is well 

 known to all who have studied Mendelism, 

 so that at present there is no need to assume 

 any other cause for sports or " mutations " as 

 De Vries calls them. 1 They are so rare in 

 nature, and so common under cultivation where 

 prepared soils are very different from the more 

 uniform conditions in the wild state, that the 

 induction has strong support in the innumerable 

 coincidences between the appearance of varieties 

 and sports in the artificially prepared soils. The 

 cabbage, for example (Brassica oleracea\ has no 

 wild varieties, but they are innumerable under 

 cultivation. The wild chrysanthemum has a 

 very small and yellow flower, yet hardly any 

 plant sports more in colour than the cultivated 

 varieties. Numerous other illustrations might 

 be given as all cultivators of flowers and 

 vegetables know. 



Since the present year began another book 

 on " Heredity " has appeared, by Mr J. Arthur 

 Thomson. Being a zoologist, like Mr Reid 



1 I have pointed out that the so-called " mutations " of CEnothera 

 have not characters of sufficient importance to be designated as 

 "species" ("Species and Varieties: their Origin by Mutation." 

 A criticism of De Vries, Journal of the Royal Horticultural Society, 

 1907). 



