36o 



NATURE 



[November 28, 1912 



Cyclopean monstrosities, in salmon and trout. 

 The author tells us that the bony fishes are speci- 

 ally important for the study of teratological varia- 

 tion ; oviparity and the abundance of eggs ensure 

 plentiful material at all stages for observation and 

 experiment, and although the major types rarely 

 live after the yolk has been absorbed, at this time 

 nearly all the organs, except the bony skeleton, 

 have attained their adult form and relations. 



Double monsters, and especially those that are 

 double at the anterior end, are so numerous and 

 variable that they require detailed classification, 

 and in his arrangement Dr. Gemmill differs from 

 his predecessors by taking into consideration the 

 internal structure. 



In addition to the chapters on the major ab- 

 normalities, which form a valuable original con- 

 tribution to vertebrate teratology, there is one on 

 minor abnormalities, which aims at facilitating 

 the task of the future worker by introducing him 

 to the literature of the subject, and should be 

 very useful for this purpose. C. T. R. 



IJher die krankhaften Erbanlagen des Matines. 



By F. Lenz. Pp. iv+170. (Jena: G. Fischer, 



igi2.) Price 4.50 marks. 

 This is an interesting discussion of the inheritance 

 of hemophilia and other sex-limited conditions in 

 man and animals, and their bearing on the deter- 

 mination of sex. In the case of haemophilia the 

 author believes that an affected man never trans- 

 mits the disease, even through his daughters to 

 his grandsons, and supposes that this is due to 

 non-viability of spermatozoa bearing the factor 

 for the affection. This conclusion is difficult to 

 accept when hajmophilia pedigrees are compared 

 with those of other sex-limited affections. He 

 also concludes that the apparent abnormalities of 

 the sex-ratio in affected families, and the excess 

 of affected members over unaffected, are likewise 

 due to incompleteness in the records. In his 

 examination of sex-limited inheritance in general 

 the author has read wfdely, but sometimes mis- 

 understands those whose writings he discusses. 

 His hypothesis of the mode of inheritance and of 

 sex-determination seems to differ more in form 

 than in substance from previously suggested 

 factorial schemes. The work as a whole is one 

 more illustration of the fact that for the solution 

 of the problem further investigation is needed 

 rather than discussion of what is already known. 



New " Contour " Wall Map of the Mediterranean 

 Lands. 40x76 inches. Scale i : 4,067,712, or 

 642 miles to one inch. (London : G. W. Bacon 

 and Co., Ltd.) Price i6i. 

 This is an effective wall map which will be useful 

 for class purposes. Two editions — with and 

 without land names — are available. The map in- 

 cludes all the countries which at any time formed 

 part of the Roman Empire, and both ancient and 

 modern names are given, when these are shown. 

 It is somewhat a disadvantage that the scheme of 

 colouring to show land relief is not that usually 

 adopted, and the blue stippling used to indicate 

 NO. 2248, VOL. 90] 



areas with less than ten inches of rainfall can be 

 seen only by a person standing near the map. 



The map is constructed on a secant conical pro- 

 jection, and it may be obtained on cloth, with 

 rollers, and varnished ; or on cloth cut to fold. 



Leather Chemists' Pocket-Book. A Short Com- 

 pendium of Analytical Methods. Edited by 

 Prof H. R. Procter, assisted by Edmund 

 Stiasny and Harold Brumwell. Pp. xiv + 223. 

 (London: E. and F. N. Spon, Ltd., 1912.) 

 Price 55. net. 

 This handy little volume is intended as an adjunct 

 to the "Leather Industries Laboratory Book," by 

 Prof. Procter, which was published in igo8. The 

 pocket-book is based uj>on the manuscript labora- 

 tory sheets, giving the course of analysis essential 

 to the practical student, in use in the authors' 

 laboratory in the University of Leeds. The book 

 should be particularly useful to students in evening 

 classes studying the science and technology of the 

 leather trades. 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for 

 opinions expressed by Jiis 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.] 



X-rays and Crystals. 



In his discussion of Dr. Lane's diagrams Dr. Tutton 

 (Nature, November 14, p. 309) invites me to consider 

 their physical aspects in the light of the crystallo- 

 graphical details which he supplies. 



The rule which I gave in a previous letter to Nature 

 (October 24, p. 219), and which Dr. Tutton has in 

 mind, is independent of all but the simplest facts of 

 crystallography. It gives a numerical method of 

 finding the positions of the spots on the diagrams, and 

 its effect is merely to show that the positions of the 

 spots give no information concerning the wave-length 

 of the incident radiation. 



In a paper read recently before the Cambridge 

 Philosophical Society my son has given a theory which 

 makes it possible to calculate the positions of the 

 spots for all dispositions of crystal and photographic 

 plate. It accounts also for the form of the spots and 

 other details, and amongst other things it explains 

 my numerical rule. It is based on the idea that any 

 plane within the crystal which is "rich" in atoms 

 can be looked on as a reflecting plane ; the positions 

 of the spots can then be calculated by the reflection 

 laws in the ordinary way. In this extended treatment 

 the facts of crystallography are of importance, but it 

 would take too long to discuss the matter in a letter. 



I should like to refer to one other point. Dr. Tutton 

 suggests that the new experiment may possibly dis- 

 tinguish between the wave and the corpuscular theories 

 of the X-ravs. This is no doubt true in one sense. 

 If the experiment helps to prove X-rays and liffht to 

 be of the same nature, then such a theory as that of 

 the "neutral pair" is quite inadequate to bear the 

 burden of explaining the facts of all radiation. On 

 the other hand, the properties of X-rays point clearly 

 to a quasi-corpuscular theory, and certain properties 

 of light can be similarly interpreted. The problem 



