152 DOMESTICATED ANIMALS AND PLANTS 
Such radical departures from type were formerly recognized 
and popularly designated as “sports,” as if nature in some 
sudden antic disposition, at play in her workshop, were disre- 
garding all ordinary laws of procedure. 
The modern name of mutants is better, and while these sud- 
den departures are often independent of crossing, it is signifi- 
cant that they frequently breed true, showing that the changes 
involved are sufficiently profound to affect the germ plasm. 
The selection and isolation of desirable mutants, therefore, 
constitutes a third method of improvement of animals and plants, 
the one most practiced by Luther Burbank. 
Origin of new and improved strains. Three methods of im- 
provement are therefore open to the breeder: (1) selection in 
imitation of nature; (2) crossing, with the understanding that 
new strains may also be shaped up by selection ; (3) mutation, 
the fortunate mutants being seized upon and made the most of 
as a free gift of nature to the breeder’s hand. 
Doubtless all these means of changes in species are in opera- 
tion everywhere in nature. Darwin expounded the first and 
De Vries the last, and a multitude of evolutionary literature 
exists. The student who is desirous of pursuing the general 
question of origin of species in nature will find the subject 
briefly sketched in Chapters NVII-NXI of Part I, with some 
‘standard references. 
Summary. When distinct races are crossed hybrids are produced be- 
tween all the characters involved. Some of these characters will blend. 
and the result will be a new combination which will thereafter dreed true 
as regards all such blended characters. 
But other characters will not blend, remaining distinct, in which case the 
gametes will continue to produce not one new and blended character, but 
both old characters in their original purity. Under the law of chance one 
fourth of the offspring would possess the character of the one parent in its 
purity, one fourth that of the other, and half would remain hybrid. 
Inasmuch as some characters are naturally dominant and others recessive, 
the recessive individuals can be detected only where the recessive stands 
