596 



NA TURE 



[August 24, 1905 



properties of X-rays, the choice of apparatus, and the 

 technique. 



In the first twenty-four pages the apparatus is 

 considered, and the remainder of the work, with the 

 exception of two short chapters, is devoted to brief 

 consideration of a number of skin affections, including 

 malignant disease. The book will certainly be of 

 service to those for whom it is intended, and many 

 practitioners who desire to become acquainted with 

 this new branch of electrotherapeutics will find it a 

 useful introduction. The work is well written and 

 unpretentious, and Dr. Cowen has succeeded in the 

 aim laid down in his preface. 



.A'eue Abhandlungen iiber den menschlicheii VerstanJ. 

 By G. VV. V. Leibniz. Translated, with introduc- 

 tion, by C. Schaarschmidt. Second edition. Pp. 

 Ixviii -t- 590. (Leipzig: Diirr'sche Buchhandlung, 

 1904.) Price 6 marks. 

 Immanuel Kant's Logik. By G. B. Jasche. Third 

 edition. New edition by Dr. W. Kinkel. Pp. 

 xxviii+171. (Leipzig: Diirr'sche Buchhandlung, 

 1904.) Price 2 marks. 

 Lazarus der Bcgrilndcr der Volkerpsychologie. By 

 Dr. Alfred Leicht. Pp. iii. (Leipzig: Diirr'sche 

 Buchhandlung, 1904.) Price 1.40 marks. 

 The first two of the above-mentioned works appear as 

 parts of the excellent " Philosophische Bibliothek." 

 The translation of the Leibniz into the philosopher's 

 native tongue appears to be all that could be desired, 

 and the introduction gives an analysis of the work. 

 We gather that some 460 explanatory notes are to be 

 found in the succeeding volume of the series. This 

 edition of " Kant's Logik " is intended to supersede 

 the uncritical one of Von Kirchmann, who relied only 

 on the second Hartenstein edition of 1868. The present 

 editor has gone back to the original text of Jasche, 

 and has also compared the other important editions, 

 the first Hartenstein and the Rosenkranz, both of 

 1838. The spelling is completely modernised. Prof. 

 Morltz Lazarus was, with Steinthal, the founder of 

 the Zeitschrift fiir Volkerpsychologie iind Sprachwis- 

 senschaft in 1859, and his works not only contain 

 much sound psychology, but are also permeated by a 

 fine ethical spirit. His long life and labours are here 

 described by a singular!}' appreciative disciple. 



LETTERS TO THE EDITOR. 

 ]The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



British Fruit Growing. 



The question of " the diversity of yield from farms in 

 the same neighbourhood " to which you referred in your 

 article on the report of the fruit committee is, as Mr. 

 Alfred Walker remarks, one of very great complexity. No 

 evidence on this subject, however, was offered to the fruit 

 committee by the numerous growers who appeared as 

 witnesses before them, and it would certainly seem to be 

 a subject more suited for investigation at an experimental 

 station than one which could be dealt with by a depart- 

 mental committee. 



Meteorological conditions are, no doubt, primarily 

 responsible for most failures of cropping, and, in a climate 

 such as that of our islands, we can never hope to do more 

 than mitigate the evil effects of inopportune cold. The 

 destruction of the blossoms is generally due — as in 1903 — 

 to cooling by radiation, and the best safeguard against 

 this form of cooling is a fairly elevated position, and a lie 

 of. the ground favourable to the draining away of the 

 cold air from the plantation. Good air drainage is prob- 

 ably more important in fruit growing than good water 

 drainage. Various means have been investigated for re- 



NO. 1869, VOL. 72] 



ducing radiation by artificial means, but the results have 

 not yet proved themselves to be successful, at any rate 

 from an economic point of view. 



The destruction of blossoms, however, is caused some- 

 times by a low atmospheric temperature produced by 

 means other than surface radiation. This was the case 

 in the present year, when the destructive cooling agent 

 was a cold wind. A warm, low situation, with plenty of 

 shelter, will afford some safeguard against damage from 

 such a source ; and these, unfortunately, are just the con- 

 ditions which will increase the danger from radiation 

 frosts. 



There is no doubt, however, that the damage done by 

 a low temperature is not always done in a direct manner. 

 A continued spell of cold weather at the blossoming season 

 is inimical to the activity of the various insects on which 

 pollination mainly depends, and we are not yet in a position 

 to say that a sluggish action of the roots and leaves may 

 not itself be directly detrimental to the process of fertil- 

 isation. The number of apples and, still more, of pears 

 which have been imperfectly fertilised, and have, therefore, 

 dropped prematurely, have been very noticeable this year. 



What part the nature of the soil plays in modifying 

 the action of cold on the trees is one which is very difficult 

 lo foretell or to determine. We can never have two 

 plantations in different soils while being in exactly similar 

 positions ; and the question whether a blossom will be 

 reduced to a lower temperature by radiation in the moist 

 air overlying a clay soil than it would be in the dryer air 

 overlying a gravel soil, or whether, if reduced to the 

 same temperature in both cases, it would suffer more in 

 the one than in the other, is a question on which we 

 cannot dogmatise. We must not be misled by the feeling 

 of cold experienced in two such cases by the human sub- 

 ject ; indeed, watering the trees and ground is one of the 

 methods suggested for obviating the effects of radiation 

 frosts. Differences of soil, also, will act indirectly in the 

 matter by affecting the root-action and the forwardness 

 of the blossoms. 



On one point, however, I think there can be no 

 doubt, namely, that the best safeguard against injury by 

 frost, where frost is inevitable, is a healthy condition of 

 the tree itself. It has been a matter of continued observ- 

 ation that with similarly situated plantations, and with 

 similar trees in the same plantation, those which are most 

 healthy will nearly always suffer least from frost. It is 

 specially noticeable that with trees which are weakly, 

 even when they carry (as will often happen) a great 

 abundance of blossom, injury from frost is very severe, 

 although the abundance of blossom should be favourable 

 to some of these being preserved from destruction. 



It is in this direction — the general health of the trees 

 and the raising of healthier and hardier varieties — that 

 success in diminishing loss by frosts will n-ost probably 

 be achieved. It is hardly probable, I think, that much 

 will be effected, at any rate in the case of apples, by 

 raising varieties blossoming late enough to escape frets. 

 These frosts, as we all know, often occur very late in the 

 year, and though every day by which the blossoming is 

 retarded must, on the average, diminish the risk of its 

 destruction, tbere would appear to be but little chance 

 of our being able to retard it sufficiently to diminish that 

 risic to any material extent. It must be remembered, 

 also, that though we might raise a late blossoming apple, 

 it is a hundred chances to one that the fruit would be 

 able to compete in the market with known varieties. 



The flowers of the large majority of English apples 

 would appear to open within a period of about ten days. 

 Observations made this year on 117 varieties gave a total 

 range of 16 days, but 98 per cent, of these varieties opened 

 within a range of 13 days, and 84 per cent, within a 

 range of g days. The extent of the variation, therefore, 

 is not sufficiently large to offer much promise of success 

 in raising a variety which would escape frost by its late- 

 ness of flowering. It is noticeable, however, that our 

 English apples appear to be rather earlier in their flowering 

 than varieties belonging to other countries, when all are 

 grown under the same conditions. The results obtained 

 at Woburn this year were as follows, the dates being those 

 of the opening of the first flowers, and the fractions of 

 dates arising, of course, through the taking of the means. 

 The number of varieties under observation are given, and 



