REVIEWS 66 1 



The remaining sections of the book deal with practical operations of the 

 forester. The information is conveyed in a clear and interesting manner and 

 includes adequate recognition of necessary deviations from ordinary European 

 practice, for instance in connexion with the water supply in nurseries and the 

 making of coppice. 



A number of instructive photographs and other illustrations add to the value 



of this work, which may be recommended not only to foresters but to all engaged 



in the cultivation of trees and shrubs within the tropics. 



Percy Groom. 



British Violets: A Monograph. By Mrs. E. S. Gregory. With an intro- 

 duction by E. Claridge Druce, M.A., F.L.S. [Pp. xxiii + 108, 32 illustra- 

 tions.] (Cambridge : W. Heffer & Sons, Ld., 1912.) 

 MRS. GREGORY, whose work on the Eu-Violas is well known, has given us a 

 useful book on this sub-genus. The proof of the value of such a work is in the 

 using. The reviewer has worked through the long series of violets in his own 

 herbarium and has found that, in most cases, the descriptions, notes and figures 

 leave but little doubt as to the identification. The notes on distinctive features, 

 when given, are very helpful and it is rather to be regretted that in some cases 

 they are not more complete. For instance, it is doubtful whether var. pseudo- 

 mirabilis of V. Riviniana, Reichb., could be determined with any certainty from 

 the account given. 



There is, perhaps, a tendency to rely too implicitly on the opinion of conti- 

 nental botanists who have examined British specimens. In the preliminary 

 stages of the study of such a "critical" iset of plants as these, it is generally 

 necessary to consult foreign experts but observation of plants in the field may 

 overrule the judgment of an absent authority — who knew nothing at first hand 

 of the habitat of the specimens under examination. Varieties of different species 

 often approximate in form, although the species are quite distinct. Hence 

 knowledge of the range of forms in any district may suggest the probability of 

 specific identity of very unlike plants— an identity at which the referee, seeing 

 only a few plants, could never guess. Indeed, a study of the range of form 

 possible for each clearly distinct species is urgently needed in all " critical " 

 groups. 



No fewer than seventeen supposed hybrids are mentioned. Some hesitation 

 is perhaps natural in accepting all of these. Indeed the authoress herself expresses 

 doubt in some cases. The whole subject of hybrids in the British Flora is worthy 

 of careful study. Combination of the characters of two well-marked species, 

 especially if accompanied by sterility, may be good evidence and probably, in 

 general and under certain conditions, it is so but direct confirmatory evidence 

 from actual crossing is desirable. In particular, doubt may well be felt in 

 approaching such a name as V. canina x V. lactea x V. Riviniana (p. 96). 



These remarks, however, are in no way intended to detract from the com- 

 mendation of the book. Mrs. Gregory did not set out to settle all the doubtful 

 points respecting the Violets. This would have required more than the twenty- 

 five years of study which she has devoted to the group. She intended to give 

 a clear working account of the violets occurring in this country and in this she 

 has very largely succeeded. 



A special word of praise must be given to Miss Mills's drawings ; these are 

 numerous and very well executed. The photographs of herbarium specimens, too, 

 are clear and helpful. 



