3 1 8 



NATURE 



[May 29, 19 r 



anatomically, for they have that kind of accuracy 

 which no artist who is not the investigator and 

 author ever can portray. 



As a work of reference and a storehouse of 

 accurate information, Prof. Eisler's monograph 

 will be invaluable. 



(3) In the notes upon the other two volumes we 

 have been dealing with facts, normal and patho- 

 logical ; but in Dr. Radl's excursion into trans- 

 cendental philosophy we are invited into the realms 

 of ultra-Bergsonian casuistry, which is certainly 

 not the normal environment of the biologist. The 

 major part of his book is devoted to a discussion 

 of the comparative anatomy of the visual organs 

 and related nervous structures, chiefly of inverte- 

 brate animals ; and the author uses these facts, or 

 rather his speculative interpretation of them, as 

 the ammunition for an attack upon the usual 

 methods of biological argument, and especially 

 upon theories of phylogenesis. It is easy to see 

 why he chose the visual organs for this purpose : 

 the data relating to the other sensory mechanisms, 

 if employed as he uses his materials, would all 

 have pointed in the direction opposite to that 

 desired by Dr. Radl. But the retina grows out 

 from the central nervous system : therefore it is 

 not formed by the influence of environment; it is 

 the material expression of the "neue Lehre " that 

 the mind makes its own instruments ! This is the 

 kind of argument, if such speculations can be 

 called argument, that Dr. Radl indulges in. It 

 seems to the reviewer that Dr. Radl has not suffi- 

 ciently acknowledged his indebtedness to Bergson ; 

 but, on the other hand, his statement lacks even 

 the superficial plausibility of Bergson's writings. 



OUR BOOKSHELF. 

 Tracks of the Sun and Stars, a.d. 1900 to a.d. 

 37900. Photographs from Stereoscopic Per- 

 spective Drawings made at Tenby, a.d. 1912-13. 

 By Thomas Edward Heath. Pp. 17 + photo- 

 graphs. (London : W. Wesley and Son ; Man- 

 chester : Flatters and Garnett, Ltd., n.d.) 

 Price 55. net. 

 It has probably occurred to many who are inter- 

 ested in the study of stellar motions that it would 

 be instructive to have a model of those star-tracks 

 which are known, so that the phenomena in the 

 three-dimensional aspect might be more easily 

 grasped. By means of Mr. Heath's stereoscopic 

 drawings it is now possible to have such a model 

 before our eyes, and to see in a vivid manner the 

 complex system of motions of a portion of the 

 stellar universe. We have been delighted with 

 the clearness with which the varying inclinations 

 and directions of the interlacing movements are 

 shown. Perhaps the most striking impression is 

 the very considerable change of relative position 

 which takes place in the selected interval of 

 NO. 2274, VOL. 91] 



36,000 years — a period by no means long from the 

 astronomical point of view. The great range of 

 difference in the speeds of the stars is also brought 

 out prominently. 



In order to ascertain the complete motion of 

 a star, the proper motion, radial motion, and paral- 

 lax must be known, the parallax being generally 

 much the most uncertain of these quantities. In 

 some cases where the value is small, Mr. Heath's 

 tracks are rather hypothetical ; but recent re- 

 searches have increased considerably the number 

 of trustworthy parallaxes, and the data used for 

 these drawings appear to be well selected on the 

 whole. Two views are given, in one of which the 

 observer is supposed to be removed 100 light-years, 

 and in the other 200 light-years, from the present 

 position of the sun. The letterpress contains use- 

 ful instructions for the reader who wishes to make 

 for himself other drawings of this character. 



A. S. E. 



Die europaeischen Schlangen. Kupferdruck- 

 tafeln nach Photographien der lebenden Tiere. 

 By Dr. Fritz Steinheil. Erstes Heft. (Jena : 

 Gustav Fischer, 1913-) Price 3 marks. 

 Although there is no lack of good figures of most 

 of the snakes of Europe, yet these are mostly 

 executed from preserved specimens. We there- 

 fore welcome the publication, of which the first 

 fascicle has just appeared, undertaken by the 

 enterprising firm of Gustav Fischer, in which Dr. 

 Steinheil intends to represent, by means of photo- 

 graphs taken from living examples, the different 

 species of snakes inhabiting Europe, as well as 

 their principal varieties. The five copper-plates 

 now issued could scarcely be surpassed. 



The letterpress accompanying each plate is 

 short, and deals merely with the geographical 

 distribution and the habits in captivity ; no 

 information is given concerning the mode of repro- 

 duction, a subject of particular interest not only 

 to the herpetologist, but also to the amateur 

 who keeps snakes in the terrarium. No system- 

 atic order is followed, but a brief introduction 

 explains the classification followed, which, as well 

 as the nomenclature, is in accordance with the 

 British Museum catalogue of snakes, also adopted 

 in Schreiber's recently issued second edition of 

 the " Herpetologia Europsea." In fact, as the 

 author tells us in the preface, this work is in- 

 tended to serve as an atlas to the " Herpetologia 

 Europaea," and as such will prove of great service. 



G. A. B. 



Die Methoden der exakten, quantitativen Bestim- 

 mung der Alkaloide. By Prof. Anton 

 Ritter von Korczynski. Pp. iv + 82. (Berlin: 

 Gebruder Borntraeger, 1913.) Price 3.50 marks. 

 This little work deals with the methods by which 

 alkaloids may be accurately determined quantita- 

 tively, but not with the methods by which the 

 total alkaloids may be extracted from crude drugs 

 or their preparations, although an appendix of 

 fifteen pages contains the details of the alkaloidal 

 drug-assays of the German Pharmacopoeia. One- 

 third of the book is devoted to the determination 



