230 PRACTICAL COURSE IN BOTANY 
Practical Questions 
1. Would hybridization account for some of the diversities mentioned! 
in 170? (See 257.) 
2. To what cases would it not apply? (256; Exp. 79.) 
3. Would it be worth while to try to hybridize the potato and squash ? 
The squash and pumpkin? The lily and rose? Sweetbrier and wild 
rose? Apple and peach? Wild crab and sweet apple? Blackberry and 
strawberry? Blackberry and raspberry? Lemon and watermelon ? 
Lemon and orange? Why, or why not, in each case? (256; Exps. 
78, 79.) 
VII. PLANT BREEDING 
Materia. — If practicable, visit a market garden, a florist’s establish- 
ment, or, lacking these, the fruit and vegetable stalls of a city market. 
260. Fixing the type. —It is the tendency of plants to 
vary under the influence of climate, soil, food supply, cross- 
ing, and other causes perhaps unknown to us, that makes 
the plant breeder’s art possible. When a horticulturist sets 
out to produce a new fruit or vegetable, he first forms in his 
mind a clear idea of what he wants— whether increase of yield 
or size, resistance to cold, drought, or disease, improvement in 
flavor, color, shape, etc., or change in the time of maturing or 
flowering (early and late varieties). Suppose, for instance, 
he wishes to produce an oxeye daisy with all the disk florets 
changed to white ones like the rays. He will begin by selecting 
plants with the greatest number of rays and the most conspic- 
uous ones that he can find, and sowing the seeds of the flowers 
which show the greatest tendency to the development of these 
qualities. He will continue this process from generation to 
generation, rigorously destroying all specimens that do not 
approach nearer the ideal sought, until all disposition to 
‘‘ rogue,’’ as the tendency to revert is called, has been elimi- 
nated. When variations cease to occur and the seed of the 
new variety always “‘come true,’’ the type is said to be fixed; 
though some care will always be necessary to keep it so, 
as the influence of changed surroundings and the danger of 
mixture with foreign pollen must always be provided against. 
