April 2%, 1881] 



NATURE 



603 



really an accurate portrait of the Korean envoy who 

 visited Japan in 1877. 



It is impossible to do justice to Dr. Rein's important 

 book in the space at our command. Its construction is 

 eminently scientific, and its thoroughness will excite the 

 admiration of all who know the difficulty of obtaining, 

 and especially of selecting, information upon many of the 

 matters so exhaustively treated. The errors are few and 

 seldom important, and will probably disappear in the next 

 edition. One powerful recommendation is the absence of 

 the ego from its pages ; the author everywhere studiously 

 keeps his own individuality concealed, and in the dis- 

 cussion of most points he is nearly always contented with 

 such a statement and grouping of the principal facts as 

 will leave the inference well within the grasp of the reader's 

 mind. In conclusion, it is the best of the many publi- 

 cations upon the subject of Japan that have appeared in 

 the last ten years, and, unlike most of the number, sup- 

 plies a real want, and will be received gratefully by all 

 who seek for solid, trustworthy information. We trust 

 that the completion of the work will soon be issued. 



OUR BOOK SHELF 

 Etudes g^om^triques et ciiihna/iques. Note siir quelques 



Questions de Geonietrie et de Ciiithnatiqtie, et Reponse 



atix Reclamations de M. V Abbe Aoust. Par E. J. Habich. 



80 pp. (Lima, 1880.) 

 M. l'Abbe Aoust, author of the "Analyse infinitdsimale 

 des Courbes planes," and our author put forward con- 

 flicting claims as to priority of discovery. 



The polemics have fired off their powder in Lcs Mondes 

 (tome iv., 1880, Aoust : tome 1., 1S79, Habich ; see also 

 the Comptes i-endus, Ixxxv., 1877, and Ixxxix., 1879), and 

 the object of the present pamphlet is " de r(fduire h. leur 

 juste valeur lcs assertions " of the Abbd The matters in 

 dispute can be inferred from the three divisions of the 

 present work :^ 



" I. Developpoides — considerations historiques, dtude 

 des enveloppes des droites par la consideration du centre 

 instantane de rotation, developpoides des divers ordres 

 et devellopoidcs inverses. 



"2. Coordonnees tangentielles-polaires. 



" 3. Mouvement geometrique d'une figure plane dans 

 son plan — considerations generales, mouvement geo- 

 metrique determine par deux systfemes d'enveloppees et 

 d'enveloppes, mouvement d'une droit sur un plan." 



We have, of course, but one side of the quarrel pre- 

 sented to us, but leaving polemics on one side there is a 

 great deal of interesting matter put before us. Time will, 

 no doubt, settle the question of priority. 



A Synopsis of Elementary Results in Pure and Applied 



Mathematics. By G. S. Carr, B.A. Vol. i. part ,viii. 



(C. F. Hodgson and Son, 1880.) 

 We recently noticed with approval the volume con- 

 taining the first seven parts. This eighth part carries on 

 the articles from 1400 to l868, and is concerned with the 

 differential calculus. It contains an abstract of the usual 

 processes, and besides gives a succinct account of the 

 theory of operations, and an analysis of matters which 

 are treated of in the higher algebra, as Jacobians and 

 quantics, and closes with maxima and minima, the 

 geometrical applications being reserved for the parts on 

 Co-ordinate Geometry. 



These fifty-six pages are very correctly printed, at least 

 we have not detected more than three or four trivial typo- 

 graphical errors. 



This part maintains the handy character for reference 

 of its forerunners. 



The Practical Fisherman. By T. H. Keene. (London : 



The Bazaar Oifice.) 

 This book deals with the natural history, the legendary 

 lore, and the capture of British freshwater fish, together 

 with the art of tackle-making. The author has bestowed 

 great care on his work, and seems to have studied every 

 book written or published on the charming subject from 

 Oppian to the present time. Mr. Keene is besides an 

 enthusiastic fisherman, and has thus produced a treatise 

 of great interest to the practical angler. We may add 

 that this work is almost the only one on angling which 

 treats of the natural as well as the traditional history of 

 fishc?. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by Ins correspondents. A'cHher can he undertake to return, 

 or to correspond until the writers of rejected manuscripts. 

 No notice is taken of anoiiyinous communications. 



[The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible othenvise to ensure the appearance even 

 of communications containing interesting and novel facts.\ 



The Movements of Leaves 



Fritz Mueller has sent me some additional observations on 

 the movements of leaves, when expo.sed to a bright light. Such 

 movements seem to be as well developed and as diversified under 

 the bright sun of Brazil, as are the well-kn iwn sleep or nycti- 

 tropic movements of plants in all parts of the world. This 

 result has interested me much, as I lon^ doubted whether para- 

 heliotropic movements were commcn enough to deserve to he 

 separately designated. It is a reii arkable fact that in certain 

 species these movements closely resemble the sleep movements 

 of allied forms. Thus the leaflets of one of the Brazilian Cassise 

 assume when exposed to sunshine nearly the same position as 

 those of the not distantly allied H:ematoxylon when asleep, as 

 shown in Fig-. 153 of "The Movements of Plants." Whereas 

 the leaflets of this Cassia sleep by moving down and rotating on 

 their axes, in the same peculiar manner as in so many other 

 species of the genus. Again, with an unnamed species of 

 Phyllanthus, the leaves move forwards at night, so that their 

 midribs then stand nearly parallel to the horizontal branches 

 from which they spring ; but when they are exposed to bright 

 sunshine they rise up vertically, ai d their upper surfaces 

 come into contact, as they are opposite. Now this is the posi- 

 tion which the leaves of another species, namely Phyllanthus 

 comptessus, assume when they go to sleep at night. Fritz 

 Miiller states that the paraheliotropic movements of the leaves 

 of a Mucuna, a large tw ining Papilionaceous plant, are strange 

 and inexplicable ; the leaflets sleep by hanging vertically down, 

 but under bright sunshine the petiole rises vertically up, and the 

 terminal leaflet rotates by means of its pulvinus th.-ough an angle 

 of 180°, and thus its upper surface stands on the same side with 

 the lower surfaces of the lateral leaflets. Fritz Miiller adds, " I 

 do not understand the meaning of this rotation of the terminal 

 leaflet, as even without such a movement it would be apparently 

 equally well protected against the rays of the sun. The leaflets, 

 also, on many of the leaves on the same plant assume various 

 other strange positions." With one species of Desmodiuia, 

 presently to be mentioned as sleeping in a remarkable uianner, 

 the leaflets rise up vertically when exposed to bright sunshine, 

 and the upper surfaces of the lateral leaflets are thus brought 

 into contact. The leaves of Bauhinia grandiflora go to sleep 

 at an unusu.illy early hour in the evening, and in the manner 

 described at p. 373 of "The Movements of Plants," namely, 

 by the two halves of the same leaf rising up and coming into 

 close contact : now the leaves of Bauhinia Brasilitnsis do not 

 sleep, as far as Fritz Miiller has seen, but they are very sensitive 

 to a bright light, and when thus exposed the two halves rise up 

 and stand at 45° or upwards above the horizon. 



Fritz Midler has sent me some cases, in addition to those given 

 in my former letter of March 3, of the leaves of closely-aUied 

 plants which assume a vertical position at night by widely dif- 

 ferent movements; ard these cases are of interest as indicating 

 that sleep-movements have been acquired for a special purpose. 

 We have just seen that of two species of Bauhinia the leaves of 

 one sleep conspicuously, while those of a second species appa- 



