456 KINSHIP AND ADAPTATION 
analogy with natural selection as Darwinians commonly 
assume. Nevertheless, cautious observation of plants and 
animals under domestication is sure to throw important 
light upon what happens in nature, for the artificial conditions 
being more under control, it is easier to estimate the effects 
which a given factor (such as heredity for instance) may 
safely be counted upon to exert. Some quite unexpected 
results have been reached through studies in the history of 
garden vegetables by Dr. E. L. Sturtevant of the New York 
State Agricultural Experiment Station. Wishing to gain 
what evidence he could of “the extent of variation that has 
been produced in plants through cultivation,” he examined 
all pictures and descriptions in the old herbals—many of 
them entirely trustworthy records although published two 
or three centuries ago—and compared them with the more 
important recent records and with living examples of the 
forms now in cultivation. It seemed not unreasonable to 
expect that among so many plants, cultivated for centuries, 
at least a few examples would be found in which extreme 
types such as cauliflower, Brussels sprouts, kohlrabi, and 
other derivations of the wild cabbage, might be connected 
by a series of slightly differing connecting links. In not a 
single case has such a series been found. So far as may be 
judged from the evidence, new types are not developed from 
other types by the cumulative selection of slight variations 
in a given direction; but they come suddenly, and each is 
distinct from its first appearance. All that the selection of 
slight variations ever accomplishes is the improvement up 
to a certain point of features already well marked; and ex- 
perience shows that this point is soon reached. A compact 
fleshy inflorescence, as of the cauliflower for instance, may 
be made more compact and more fleshy within certain rather 
narrow limits, and the highest degree of perfection can be 
maintained only by the most careful cultivation and generous 
enrichment of the soil. We have already seen that carrots 
under cultivation exhibit similar limitations. Such facts 
are as unfavorable to Lamarckism as to Darwinism since 
both suppose that types have always evolved through slight 
changes. | : 
