BOOK REVIEWS. 



355 



itself to the changing conditions. The power of response and adjust- 

 ment is the most characteristic feature of Life." 



He applies this to the root only : but it is equally applicable to 

 every organ of a plant, both morphologically, as seen externally, and 

 anatomically, within. 



The University of Cambridge puts it in a question on Ecology : 

 " Mention any characters of the plants selected [previously mentioned] 

 which you might regard as developed in relation to their respective 

 habitats." The words we have italicized refer generally to all parts 

 of all plants characteristic of well-defined associations, as Xerophytes, 

 Hydrophytes, &c. " The Study of Plants " can scarcely answer this 

 question in full. 



" The Mutation Factor in Evolution, with Particular Reference 

 to Oenothera." By R. Ruggles Gates, Ph.D., F.L.S. 8vo. 

 xy i + 353 PP- (Macmillan, London, 1915.) 10s. net. 



Everyone recognizes the fact of heredity, but its mechanism is little 

 understood. Mendel's work threw a little light upon it and acted as a 

 guide to further investigation, but full knowledge is not yet. Still less 

 is the origin of the variations which give rise to new forms understood. 

 Some look to the direct action of the environment, some to crossing, 

 some to mutation, some to inherent variability ; the author deals with 

 the role of mutation. Mutations he regards as the expression of some 

 germinal change, the origin of which is, however, a mystery. The 

 results of his work lead him to conclude that mutations occur quite 

 apart from crossing either in the preceding generation or in any pre- 

 ceding generation, and he examines the evidence for this view, much 

 of which has been accumulated by his own energy, and which relates 

 largely to the forms of Oenothera Lamarckiana upon which de Vries 

 built his Mutation Theory. He has produced a masterly review of 

 our knowledge of the matter, and withal a readable one. Many of his 

 results appear at variance with Mendelian expectations, and they raise 

 interesting and important questions for those who believe all problems 

 of genetics may be solved by the application of the idea of unit charac- 

 ters. The case of peas which Mendel investigated was comparatively 

 simple, though less simple than at first appeared, for many difficult 

 problems have arisen since the repetition of his experiments began, 

 and other plants are proving less amenable to the formulae which have 

 been derived at present. 



"The Hobby Gardener." By A. C. Marshall, F.R.H.S. 8vo. 

 119 pp. (Pearson, London, 1915.) is. net. 



Written for the owners of small or villa gardens. The author has 

 kept enthusiastic gardeners always in mind by writing his instruc- 

 tions plainly, with capital explanatory diagrams, and giving clear 

 suggestions of what should be done month by month to keep the 

 garden attractive, and to develop the healthy hobby of the owner. 

 The book is nicely printed, and possesses a good index. 



