June 17, 1920] 



NATURE 



483 



relating to the r6le of the nucleus and the chromo- 

 somes in development. Another section gives a 

 short account of the chondriosomes, while the 

 final chapter is concerned with the nucleus in the 

 Protista and the nuclear relationships in plants. 



The book is well illustrated and excellently pro- 

 duced. While it can scarcely appeal to a wide 

 circle of readers, it will be of great service to all 

 those who wish to be informed concerning the 

 results arising out of the work of the last twenty 

 years on this subject. The cytologist will find it 

 indispensable for reference, and biologists gener- 

 ally will turn to it for the more recent work 

 relating to these problems. R. R. G. 



Our Bookshelf. 



Aircraft in Peace and the Law. By Dr. J. M. 

 Spaight. Pp. viii + 233. (London : Macmillan 

 and Co., Ltd., 1919.) Price 85. 6d. net. 



This is a useful attempt to put before the public 

 the main issues of international law relating to 

 the air. In every new development of modern 

 invention, law-making authorities are faced with 

 the difficult task of applying old principles to 

 developments not contemplated when those prin- 

 ciples were formulated, and with such a revolu- 

 tionary departure as the modern aircraft there is 

 a grave risk of deception by a false analogy. The 

 British method has been to apply as far as pos- 

 sible the principles of the Merchant Shipping Acts 

 to aircraft. The idea is lacking in boldness and 

 imagination, for there is little parallel between 

 the two forms of navigation in relation either to 

 the problems of the navigators themselves, or to 

 the rights and liabilities of the public at large. 

 Generally speaking, however, a wise caution has 

 been exercised by those who framed the Inter- 

 national Convention. From another point of view 

 the fundamental issue in aerial navigation is the 

 sovereignty of the air, and on this England re- 

 served her opinion. Continental Powers, with- 

 out exception, clearly realising the serious mili- 

 tary problems before them if all comers were 

 allowed unrestricted flight above their territories, 

 maintained in full their dominion in the air above 

 their lands and territorial waters. England, on 

 the other hand, had a different problem to face. 

 No aerial highway of any importance crosses her 

 frontiers in any part of the world,, but nearly all 

 the aerial routes which link yp her scattjered 

 dominions do almost invariably cross the terri- 

 tories of other nations ; she ought, therefore, her 

 aerial experts maintained, to hold out for free 

 flight. 



It would seem that this view exaggerated the 

 difficulties put in the way. of innocent traffic by 

 the maintenance of sovereignty, and minimised 

 the dangers of sudden invasion. We must not 

 forget that tlie economic interests of Great Britain 

 are just as dependent oh military security as they 



NO. 2642, VOL. 105] 



are on theoretical freedom of transport, and 

 therefore Dr. Spaight would seem to be' quite 

 correct in urging the maintenance of the doctrine 

 of the sovereignty of the air. Popular panic is 

 a disaster only less serious than actual assault. 

 The book is well arranged and indexedj while the 

 writer's comments on what is as yet alnKJSt an 

 untested department of law of exceptional diffi-, 

 cultv, are acute, unprejudiced, and well-inforrried. 



W. B. F. 



Wireless Telegraphy and Telephony : First Prin- 

 ciples, Present Practice, and Testing. By 

 H. M. Dowsett. Pp. xxxi-i-331, (London: 

 The Wireless Press, Ltd., 1920.) Price gs. 

 The object of this work is to provide a connect- 

 ing link between the various elementary text- 

 books, intended for those taking up the study of 

 wireless telegraphy, and advanced treatises deal- 

 ing with particular aspects or branches of the 

 subject. It does not aim at completeness, but 

 usefully develops certain parts of the theory and 

 practice involved. The author insists upon an 

 adequate appreciation of the structure of the atom 

 and the part played by its constituents for a clear 

 understanding of the phenomena met with in 

 wireless working, and puts forward conceptions 

 which, if not presenting a perfectly true scale 

 model of the atom, at any rate are helpful in 

 fixing the ideas. Another theoretical chapter leads 

 up to explanations of some of the methods used 

 in spark and continuous-wave transmission ; and 

 perhaps the most important sections of the book 

 deal with the thermo-ionic valve and the modern 

 methods of its employment for both reception and 

 transmission, upon which so much of the recent 

 advances depends. Other developments dealt with 

 are high-speed automatic transmission and direc- 

 tion finding. A considerable portion of the book 

 is devoted to systems of measurement of electrical 

 quantities adapted to wireless telegraph testing. 

 The author concerns himself only with up-to-date 

 methods, and historical matter does not form part 

 of his scheme. 



Chimica delle Sostanze Esplosive. By Prof. 

 Michele Giua. Pp. xvi-f-557. (Milano r Ulrico 

 Hoepli, 1 919.) Price 28 lire. .• 



This treatise is written from the point of view 

 of the laboratory chemist, and contains a very. 

 full account of the chemistry of explosive, com- 

 pounds. The author bases his work on -that of. 

 Berthelot, and develops the theoretical treatment 

 pf, explosive reactions on thermochemical lines. 

 When dealing with the propagation of explosions 

 through gases, the work, of British ihvestigfators 

 IS practically unnoticed, and although a fgW'Mfef- 

 ences to papers do indeed appeai- in a table, they 

 are omitted from the index. The treatment . ofi- 

 this part of the subject thus appears tol^.fathi^r^, 

 superficial. The explosive .compounds,, are di^r, . 

 Sfcribed fully, and brief,, but clear, account^ _are 

 jgiven of the plant used ini their manufacture.' Thfs' 

 section, wifK its numerous references tothe Hfbra- 



