CHAPTER XII 
PLANT BREEDING 
164. The basis of plant breeding. It is the business of the 
professional plant breeder to discover or originate desirable 
varieties of plants and then to perpetuate them. As soon 
as he becomes certain that he has obtained a really valuable 
new variety, he proceeds to multiply it until he can offer to 
growers everywhere its seeds, bulbs, or other means of repro- 
ducing it. 
The possibility of producing new varieties rests largely 
upon two highly important facts: 
1. That all the higher plants vary from generation to 
generation. 
2. That the higher plants sometimes mutate. 
Variations are familiar enough to every observing person. No 
two corn plants, bean plants, or tomato plants are just alike, 
even though they may have been grown from seed from the 
same ear, the same bean pod, or the same tomato. The varia- 
tions may be noticed in the root, stem, leaf, flower, or fruit, 
or in several or all of these. The term mutation is less com- 
monly used than the term variation. It is the scientific name 
for the kind of abrupt appearances of forms, extremely unlike 
the parent, long known to horticulturists as sports. A single 
bud upon a peach tree may mutate and produce a branch which 
will bear nectarines, and a bud upon a tree which bore purple 
plums has been observed to grow into a branch which bore 
only yellow plums of a kind previously unknown. Some of 
the most valuable varieties of the grains are seed sports, or 
mutations first noticed in the seedling grown from the seed 
of a very different variety. 
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