EVOLUTION BY CHOICE 463 
some salt in them already, and this might favor the seedlings 
enduring a larger amount of salt as they grew. Sooner or 
later the constitutional equilibrium of the plants would be 
so disturbed that a mutation would result. Several successive 
mutations might occur as seeds fell into salter and salter 
localities. At last would appear a form like our seaside 
crowfoot (Fig. 303) able to thrive where the salt is strong 
and showing many marks of its effect. The first mutation 
would give an hereditary salt-preferring type, while a succes- 
Ky a) a 
ANS 
“fd WESSON 
2 
Fic. 303.—Seaside Crowfoot (Ranunculus Cymbalaria, Crowfoot Family, 
Ranunculacee). (Britton and Brown.)—Perennial herb 4-22 cm. tall; 
leaves fleshy, smooth throughout; flowers yellow; fruit dry. Native 
home, Northern North America and Eurasia. 
sion of mutations caused by similar responses would produce 
a distinct species. 
The case of our stranded buttercups might be paralleled 
by an animal which in time of famine, was reduced to the 
choice of eating or rejecting unaccustomed food, and as a 
result of eating enough of it to sustain life, being modified 
in its habits and structure to the point of producing muta- 
tions. Whatever share in the final result of such an evolu- 
tionary process we may attribute to acquirement or to selec- 
tion we are still free to believe that it is the choice of 
