1907] CURRENT LITERATURE 



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principle of single-ear selection, started by Hopkins of the University of TUinois. 

 The main difference in the breeding of corn and other cereals is that among the 

 latter cross-pollination is an exception, while with com it is the rule, and repeated 

 selection becomes necessary to eliminate the effects of previous crosses (not for 

 slow improvement, as commonly supposed). One catches glimpses of the 

 immense possibilities in breeding corn, as w^ell as the amateurishness of our 

 current methods. 



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The fourth topic is entitled *'The production of horticultural novelties by 

 Luther Burbank/' who has the misfortune of being both overestimated and 

 underestimated. No one is better equipjx^d than DeVries, through training and 

 temperament, to reach a true estimate, and hence this section of the volume is of 

 great interest. The topic is presented under four divisions, the first dealing with 

 "Methods and material." Burbank is described as "a man who devotes his 

 whole life and all his energies to the introduction and production of new, beauti- 

 ful, and useful horticultural plants," and who has rediscovered many of the prac- 

 tices more or less universally known in Europe. A special feature of his work 

 is the large scale on which his selections are made; and his main work consists 

 in the production of new horticultural varieties by crossing, getting combinations 

 of desirable qualities, and eliminating undesirable ones. The second section gives 

 details of the conspicuous "New varieties of fruits and flowers" originated by 

 Burbank, There is an analysis of the simpler methods of producing what are 

 called "new varieties" in horticulture, with illustrations from some of Burbank's 

 most notable achievements, so far as the author could get at the scientific side 

 of his performances by questioning. The general conclusion to be drawn from 

 his operations is that combinations of characters can be obtained by crosses in 

 almost any arbitrarily chosen direction or degree, but that new unit-characters 

 are probably never produced. The third section deals with "Hybridization 

 and selection" as practiced by Burbaxk. The aim of the hybridizer is to uj^set 

 the constancy of his plants and produce an extreme chaos of forms, from w^hich 

 his selections may be made. To get the real pedigree of any plant in this chaos 

 is impossible, and the hybridizer does not care, for he is only after the results. 

 Burbank is credited with ''a special gift of judgment" in his selections, but 

 his results are new combinations of characters and not the production of new 

 characters. All such practical hybridizing and selection "afford highly valuable 

 resources for theoretical discussion, but on single points they should not be 

 accepted as definite proofs, but only as indications for more circumscribed experf- 

 ments." The last section, entitled "Mutations in horticulture," shows that 

 most new horticultural varieties originate as "chance seedlings," many illustra- 

 tions from BuRBAXK^s work being used to show that it is the occasional "chance 

 plant" with some peculiar character that has been seized upon and propagated. 

 It would seem, therefore, that mutations in horticulture have been frequent. 



The very important fifth topic is "The association of characters in plant 

 breeding," and it is presented in five sections. The first discusses "Association 

 of characters in nature," and shows that there is a regular coincidence of marks 



