CURRENT LITERATURE 



BOOK REVIEWS 



i 



Plant breeding 



Professor DeVries has contributed a most interesting volume^ to the 

 literature of plant breeding and its relations to the current theories of evolution. 

 It is a compact and popular presentation of the recent wonderful development 

 in methods of plant breeding, and a clear statement of the bearing of all this 

 vast experimental work upon the author's theory of mutation. Of special interest 

 to American readers are the description of the methods and the results obtained 

 at the Swedish station at Svalof under NiLssoN, and the comments upon the 

 work of Burbank. The work of the former will come to many as a revelation, 

 and the work of the latter will be better understood. 



The material of the book is derived chiefly from a series of lectures given during 

 two summers at the University of California and the University of Chicago. It 

 is presented under a series of topics, each of which is complete in itself, but all 

 of which contribute to the general purpose of the author, as expressed above. 

 This accounts for a certain amount of repetition, but it is the kind of repetition 

 that uses the same material to illustrate the various points of view involved in a 

 great conception. It is difficult to give an adequate idea of the contents of such 

 a book, for the principles become convincing only when illuminated by the details 

 of experimental work. 



The first topic, entitled "Evolution and mutation," is a general introductory 

 definition of the mutual relations of evolution, natural selection, and mutation, 

 relations that seem to be persistently misunderstood. Unit-characters, as the' 

 essential feature of mutation, are defined; and hybridization is shown to result, 



not in new unit-characters, which characterize mutation, but simply in a new com- 

 bination of unit-characters. This position is supported, not only by the author's 

 experiments, but by numerous cases in horticulture, by the constancy of wild 

 species, by the behavior of characters in crosses, by the occurrence of clearly 

 defined small species within the ordinary species of wild plants and agricultural 

 crops. It is claimed that the slow change of one s])ecies into another has not 

 been proved, and that the mass of present evidence points to the origin of species 

 from other species by "sudden leaps," which are called mutations. 



The second topic deals with "The discovery of the elementary species of 

 agricultural plants by Hjalaur Nilssox," whose work the author evidently 



' DeVries, Hugo, Plant-breeding; comments on the experiments of Nilsson and 

 Burbank. Pp. xiii-f 360. Chicago: The Open Court Publishing Co. 1907. 



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