MaV 



' V03 I 



NA TURE 



i\.-,ico-cli(inu;il analysis, pp. 206 to 251; and lastly, 

 If most interesting account given on pp. 272 to 315 

 t the physical chemistry of ferment action, and of 

 Bredig's recent discovery of inorganic ferments. 



The whole volume well deserves careful reading, 

 and it is to be hoped that it will find a wide circle 

 of readers amongst workers in all divisions of the very 

 romprehensive subject of biology. 



Benjamin Moore. 



OUR BOOK SHELF. 



Contribution a V Etude ^du Mode de Production de 



V Electricity dans les Etres vivants. Par M. la Dr. 



Louis Querton, Pp. 180. (Bruxelles : Lamartin, 



1902.) 

 This contribution to the existing literature upon 

 the subject of vital electromotive phenomena con- 

 tains some new researches which support the view 

 advocated by the author that the electrical changes in 

 living tissues are caused by definite chemical 

 processes. The view is not a new one, and its 

 advocacy in the present publication appears to have 

 been called forth by the attitude taken by Mendelsohn 

 in his article upon the subject in the " Dictionnaire de 

 Physiologie," edited bv Prof. Richet ; this attitude is 

 described by Dr. Querton in the following quotation 

 from M. Mendelsohn's article:— 



" The conception of the chemical origin of the elec- 

 trical phenoniena observed in nerve and muscle is 

 purely hypothetical." 



Dr. Querton has done useful service in bringing 

 together additional evidence that the electrical pheno- 

 mena are in many cases the indications of definite 

 chemical processes. The author gives a brief review of 

 the general features of the phenomena in electrical 

 organs, muscles, nerves, the eye, glandular tissue, the 

 skin and the leaves of plants ; he then describes observ- 

 ations of his own as to the direct connection between 

 such electrical phenomena in plant leaves as are pro- 

 duced by the action of light and (photo-)chemical 

 changes' in the chlorophyll ; he follows these by a de- 

 scription of photo-electric phenomena occurring in 

 solutions of oxalic acid, &c. 



As regards the general review, this is admittedly 

 scanty, particularly in the part which deals with the 

 electric organs of fishes, and in dealing with this 

 portion of the subject the author does not appear to 

 have recognised that recent observations point to the 

 conclusion that the electrical organs of fishes are to 

 be classed among nervous, and not among muscular, 

 structures. The author's own researches show that 

 electromotive effects may be rapidly developed, and 

 may rapidly subside in correspondence with the similar 

 development and subsidence of chemical changes of 

 comparatively small amount, and this result appears 

 to support the view of chemical causation which he 

 advocates. It must, however, be admitted that in 

 nervous tissues, chemical change is so slight or so 

 masked as to give no indications of its occurrence un- 

 less, indeed, the electrical alterations are assumed to 

 be such indications, an assumption which, for the 

 purpose of the argument, is logically unsound. Even 

 in the case of the pronounced electromotive effects ob- 

 served in the electrical organs of fishes there is the 

 same lack of evidence, and it would therefore seem that 

 provided the chemical change is of a certain type, a 

 relatively insignificant chemical alteration may be 

 associated with very definite electromotive effect; in 

 this connection the possibility of the occurrence of sur- 

 face tension changes as the result of chemical alter- 



NO. 1749, VOL. 68] 



ation might have been treated by the author with great 

 advantage. 



The impression left on reading the author's con- 

 clusions is that, although these indicate that one ante- 

 cedent of the electromotive phenomena observed in 

 living tissues is chemical change, the more interesting 

 question as to whether this chemical antecedent is a 

 remote or an immediate factor in their causation re- 

 mains untouched. 



Statics by Al'gebraic and Graphic Methods. By LewU 



J. Johnson, C.E. Pp. viii+134; with six plates. 



(New York: Wiley and Sons ;' London : Chapman 



and Hall, Ltd., 1903.) Price 2 dollars. 



From the preface we infer that the author has set out 



with the object of providing engineering students with 



a text-book of small compass in which the elementary 



parts of statics are treated on a deductive basis, and 



analytical and graphical methods of solution are treated 



side by side. 



It cannot be said that the book fulfils either of these 

 objects as adequately as it should. The proofs of the 

 conditions of equilibrium and of the parallelogram of 

 forces are so unsound that it would be far better to 

 replace them by a few definite axiomatic statements. 

 As an example, take the statement in the footnote on 

 p. 14 (in connection with the moment of a force about 

 a point), " P'or assuming the point to be fixed is 

 really assuming it to be always subject to a force equal, 

 opposite and parallel to the given one." 



In regard to the graphic solution of problems, it is 

 possible that when a student has been told how to 

 draw a force diagram, he may apply the method to 

 an example, and actually measure the lines represent- 

 ing the forces, the only drawback being that in the 

 questions the angles of the figures are not specified, 

 and the figures are too small to give good scale dia- 

 grams without this help. The so-called algebraic solu- 

 tions are too suggestive of the well-known type of 

 examination answer, " By taking moments the result- 

 ant can be found." This usually means that the 

 candidate cannot find it. The best feature of the book 

 is the set of six typical problems which are actually 

 solved by both methods on the plates at the end. 

 De I'Expdrience en Gdometrie. Par C. de Freycinet. 

 Pp. 178. (Paris : Gauthier Villars, 1903.) Price 4 

 francs. 

 The author discusses the question whether geometry 

 is purely a rational science or whether it also possesses 

 an experimental side. The question is dealt with in 

 connection with (1) the concepts of geometry, (2) geo- 

 metrical axioms, and (3) the propositions the estab- 

 lishment of which forms the object of deductive geo- 

 metry. In the first chapter, M. de Freycinet finds no 

 a priori reasons for the existence of such concepts as^ 

 space, straight line, curved line, plane or curved sur- 

 face, volume, angle, parallelism, tangency. These 

 and other concepts are all suggested to us by our per- 

 ception of the material universe. Passing on to the 

 axioms relating to the straight line and plane, the 

 author considers that it can in no sense be regarded 

 as a self-evident truth that the straight line is the 

 shortest line between two points, that a straight line 

 can be produced indefinitely in either direction, or that 

 two straight lines cannot have two points in common. 

 These and other similar facts can only be regarded as 

 results of experience and observation. In comparing 

 the purely geometrical methods of the ancients with 

 the analytical methods of Descartes and Leibnitz, the 

 latter methods will be found in reality to be no less 

 concrete in their foundations than the former. They 

 do not discuss the geometrical truths of which they 

 make use, but they accept them as evident, relying ork 

 pure geometry to establish them. 



