Hayes and Garber - Cucurbit Breeding

6 BREEDING CROP PLANTS
more attention to the planting of their crops so that those of like
kind did not grow so near each other that crossing through the
aid of insects would take place.
Sprengel, in a book published in
1793, showed the important role played by insects in pollination
and studied the adaptations for crossing found in many flowers.
He concluded that nature intended flowers should not be pollinated
by their own pollen.
The Great Hybridist Gartner. In extent and number of his
experiments Gartner's work is very great. In 1835 he heard of
the offer of a prize made by the Dutch Academy of Sciences at
Haarlem regarding the place of hybridization in producing
new varieties of economic and ornamental plants.
Gartner's paper on this question, which received the prize, was
published in extended form in 1849. He made thousands
of crosses, involving nearly 700 species, and obtained about 250
hybrids. The work was so carefully controlled and checked
that the fact of sex in plants was thoroughly proved. He
made a classification of hybrids according to whether they
resembled one or the other parent in all respects, whether they
resembled one parent in one part of the plant and the other
parent in some other characters, or whether there was an almost
equal balance. In the last case in later generations, the inclination
toward the one or the other parent was supposed to be
due to a slight overbalance of one or the other of the fertilizing
materials. Gartner explains the appearance of the first hybrid
generation as due to an inner force operating according to law.
He, like Koelreuter and Weigmann, observed increased vigor in
hybrids.
He made experiments to determine the immediate effect of
pollen with crosses between colorless and colored pericarp
varieties of maize and in crosses between a brown-seeded Lychnis
and one with a gray seed. As no change occurred, a law was
developed to the effect that pollen does not immediately affect
forms and external characters of seeds but influences the development
of the resultant plant. He observed an immediate effect
in some pea crosses and learned that the yellow cotyledon color
dominated the green in the hybrid seeds.
Early English Plant Breeders. Knight, Goss, and Herbert,
three English workers, did much to develop the art of breeding.
Knight, who was a practical horticulturist, recognized the aid
of artificial cross-pollination in producing new kinds. He