444 KINSHIP AND ADAPTATION - 
It has been thought by many naturalists that the differ- 
ences among plants and animals may best be accounted for 
as peculiarities which have arisen in individual acquire- 
ments, these having become hereditary and thus characteris- 
tic after many generations of similar response to a similar 
environment. Suppose, by way of example, that some of 
the seedlings from primitive marsh-marigolds grew in a 
rather dry locality and were more or less shaded by over- 
growth. They might be expected to respond to the lessened 
light by elongation of the internodes and leaf-stalks, while a 
Fic. 302.—Pigmy Buttercup (Ranunculus pygmeus, Crowfoot Family, 
Ranunculacee). Plant. Flower. Fruit. (Britton and Brown.)— 
Perennial (?) herb 5-12 cm. tall; flowers yellow; fruit dry. Native 
home; northern America and Eurasia. 
finger-like lobing of the blades through increased growth along 
the ribs and scant growth of the pulp between the stem 
would be fortunate as enabling the leaves to catch more of 
what little light there was. But the less favorable conditions 
for food-making would render it impossible for them to form 
and feed as many seeds as the marsh plants had done; hence 
some of the later-formed ovules would be more or less starved. 
From the good seeds formed by these pioneer plants and 
scattered in the vicinity, a second generation would arise, 
the individuals of which would respond similarly to the same 
trying conditions. Innumerable generations might follow, 
