HISTORICAL ACCOUNT OF EVOLUTION THEORY 41 
who were engaged in crossing the garden peas with a view to producing 
more vigorous and productive varieties, and Naudin (1862) in France, 
who made a comprehensive survey of the facts of hybridization in 
plants and came very near'to expressing the generalization which 
Mendel reached four years later.’ 
MENDEL’S LAW 
“The earliest experimental investigations of heredity,” says 
Locy' in a concise summary of Mendel’s work, “‘were conducted with 
plants, and the first epoch-making results were those of Gregor Mendel 
(1822-1884), a monk and later abbot, of an Augustinian monastery at 
Briinn, Austria. In the garden of the monastery, for eight years 
before publishing his results, he made experiments on the inheritance 
of individual (or unit) characters in twenty-two varieties of garden 
peas. Selecting certain constant and obvious characters, as color, and 
form of seed, length of stem, etc., he proceeded to cross these pure 
races, thus producing hybrids, and thereafter, to observe the results of 
self-fertilization among the hybrids. 
“The hybrids were produced by removing the unripe stamens of 
certain flowers and later fertilizing them by ripe pollen from another 
pure breed having a contrasting character. The results showed that 
only one of a pair of unit characters appeared in the hybrid of the next 
generation, while the other contrasting character lay dormant. Thus, 
in crossing a yellow-seeded with a green-seeded pea, the hybrid genera- 
tion showed only yellow seeds. The character thus impressing itself 
on the entire progeny was called dominant, while the other that was 
held in abeyance was designated recessive. 
“That the recessive color was not blotted out was clearly demon- 
strated by allowing the hybrid generation to develop by self-fertiliza- 
tion. Under these circumstances a most interesting result was 
attained. The filial generation, derived by self-fertilization among 
the hybrids, produced plants with yellow and green seeds, but in the 
ratio of three yellow to one green. All green-seeded individuals and 
one-third of the yellow proved to breed true, while the remaining two 
thirds of the yellow-seeded plants, when self-fertilized, produced 
yellow and green seeds in the ratio of three to one. 
“Subsequent breedings gave an unending series of results similar 
to those obtained with the first filial generation. 
t William A. Locy, The Main Currents of Zotlogy (Henry Holt & Company, 
1918), Pp. 37-39. 
