86 
DARWINISM 
CHAP. 
which the whole mode of growth has been altered, numerous 
little heads of leaves being produced on the stem. In other 
varieties the ribs of the leaves are thickened so as to become 
themselves a culinary vegetable ; while, in the Kohlrabi, the 
stem grows into a turnip-like mass just above ground. Now 
all these extraordinarily distinct plants come from one original 
species which still grows wild on our coasts ; and it must have 
varied in all these directions, otherwise variations could not 
have been accumulated to the extent we now see them. The 
flowers and seeds of all these plants have remained nearly 
stationary, because no attempt has been made to accumulate 
the slight variations that no doubt occur in them. 
If now we turn to another set of plants, the turnips, 
radishes, carrots, and potatoes, we find that the roots or under¬ 
ground tubers have been wonderfully enlarged and improved, 
and also altered in shape and colour, while the stems, leaves, 
flowers, and fruits have remained almost unchanged. In the 
various kinds of peas and beans it is the pod or fruit and the 
seed that has been subjected to selection, and therefore greatly 
modified; and it is here very important to notice that while 
all these plants have undergone cultivation in a great variety 
of soils and climates, with different manures and under 
different systems, yet the flowers have remained but little 
altered, those of the broad bean, the scarlet-runner, and the 
garden-pea, being nearly the same in all the varieties. This 
shows us how little change is produced by mere cultivation, 
or even by variety of soil and climate, if there is no selection 
to preserve and accumulate the small variations that are con¬ 
tinually occurring. When, however, a great amount of modifi¬ 
cation has been effected in one country, change to another 
country produces a decided effect. Thus it has been found 
that some of the numerous varieties of maize produced and 
cultivated in the United States change considerably, not only 
in their size and colour, but even in the shape of the seed when 
grown for a few successive years in Germany. 1 In all our 
cultivated fruit trees the fruits vary immensely in shape, size, 
colour, flavour, time of ripening, and other qualities, Avhile the 
leaves and flowers usually differ so little that they are hardly 
distinguishable except to a very close observer. 
1 Darwin, Animals and Plants under Domestication, vol. i. p. 322. 
