316 BIOLOGY AND ITS MAKERS 
of the pea, but not visible. When peas of different color 
were cross-fertilized, one color would be stronger apparently 
than the other, and would stand out in the hybrids. This 
was called the dominant color. The other, which was held 
in abeyance, was called recessive; for, though unseen, it was 
still present within the young seeds. That the recessive 
color was not blotted out was clearly shown by raising a 
crop from the hybrid, a condition under which they would 
produce seeds like those of the two original forms, and in 
equal number; and thereafter the descendants of these peas 
would breed true. This so-called purity of the germ-cells, 
then, may be expressed in this way: ‘The hybrid, whatever 
its own character, produces ripe germ-cells, which produce 
only the pure character of one parent or of the other” 
(Castle). 
Although Mendel’s discovery was for a long time over- 
looked, happily the facts were re-discovered, and at the 
present time extensive experiments are being made with 
animals to test this law: experiments in the inheritance of 
poultry, the inheritance of fur in guinea-pigs, of erectness 
in the ears of rabbits, etc., etc. In this country the experi- 
ments of Castle, Davenport, and others with animals tend 
to support Mendel’s conclusion and lift it to the position of 
a law. 
Rank of Mendel’s Discovery.—The discovery by Mendel 
of alternative inheritance will rank as one of the greatest 
discoveries in the study of heredity. The fact that in cross- 
breeding the parental qualities are not blended, but that they 
retain their individuality in the offspring, has many possible 
practical applications both in horticulture and in the breeding 
of animals. The germ-cells of the hybrids have the dominant 
and the recessive characters about equally divided; this will 
appear in the progeny of the second generation, and the races, 
when once separated, may be made to breed true. 
