;64 



NATURE 



[August 19, 1897 



of investigators, we may trust that the museums and 

 naturalists of India will avail themselves of it in order 

 to advance the subject by serious work, and thus render 

 a second edition necessary. We may point out that in 

 such case it would be well, in the bibliographical re- 

 ferences, to distinguish those that relate to habits and 

 biology from those that are systematic and nomen- 

 clatorial. D. S. 



OUR BOOK SHELF. 



A Contribution to the History of the Respiration of Man. 



By William Marcet, M.D., F.R.C.P., F.R.S. Pp. 1 16 ; 



charts and diagrams. (London : J. and A. Churchill, 



1897.) 

 The book before us comprises the subject-matter of the 

 Croonian lectures delivered before the Royal College of 

 Physicians in 1895, ^"^^ ^" appendix, which latter 

 contains a full description of the methods of investigation 

 employed by the author. The first lecture contains a 

 discussion of respiration from a general biological stand- 

 point, and concludes by giving the effects of muscular 

 exercise upon the production of CO2, and the tempera- 

 ture of the body. The second lecture is devoted to 

 human respiration ; the different forms of breathing, and 

 the absorption of oxygen in the body are considered in it. 

 In the third lecture the effect of volition upon respiration 

 is discussed, simple volition towards any kind of muscular 

 exercise, i e. volition without any response being attended 

 by an increased production of CO.j, and an increased 

 absorption of O. The question to what extent response 

 to volition can be checked is, with regard to the author's 

 deductions, of the greatest importance. In any case the 

 volition exerted is not simple volition to increased breath- 

 ing or muscular movement, but volition to the movement 

 in question -H volitional inhibition of the movement. 

 The results of the author in this direction will almost 

 certainly attract the attention of psychologists. In the 

 fourth lecture the author discusses the changes in respira- 

 tion produced by changes in the pressure of the atmo- 

 sphere breathed, and concludes by showing the influence 

 low atmospheric pressure exerts in checking volition. 

 The appendix comprises a description of the methods 

 used, and numerous experimental protocols. 



The book must be regarded as a valuable contribution 

 to the physiology of man. It is to be regretted that no 

 general index, and no headings to the chapters are given. 

 The summaries at p. 70 in the text could have been 

 placed to much greater advantage at the head of their 

 respective chapters. It is to be hoped that the sphere of 

 usefulness of the book will not be curtailed by this 

 omission. F. W. T. 



Untersuchungen ueber den Bau der Cyattophycien und 

 Bacterien. Von Prof. Dr. Alfred Fischer. Mit 3 lith. 

 Tafeln. (Jena : verlag von G. Fischer, 1897.) 



The author gives a critical and literary account of the 

 structure of the cells of bacteria and of the blue-green 

 algJE, which possess many features in common. He 

 comes to the conclusion, in opposition to many other 

 investigators, that no real nucleus, or nucleus-like body 

 is really present, but he considers that the colour of the 

 algai is to be regarded as localised in a chromatophore. 



A great part of the book is devoted to an account of 

 the methods in vogue in connection with researches into 

 these minute histological details, and Dr. Fischer's 

 criticisms will be read with interest by all who remember 

 the fine work he has already done, especially in elucidating 

 the structure of bacteria. 



NO. 145 1, VOL. 56] 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions ex- 

 pressed by his 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. '\ 



A Brilliant Perseid. 



In the hope of being able to record photographically the 

 passage through our atmosphere of some of the August meteors, 

 I exposed during the night of August 12 three photographic plates, 

 one towards the pole star, and the other two towards the con- 

 stellations of Perseus and Lyra. On the plate exposed to the 

 latter constellation absolutely no trace of any meteor trail can be 

 seen, but on the other two a very definite and distinct trail, 

 peculiar for the different degrees of condensation in it, is easily 

 visible. From the position and similarity of the trail on the 

 two plates, there is no doubt that the same meteor was in 

 question. These two plates were exposed in cameras, 

 one a 5 X 4 with a Zeiss double combination lens of 224 

 millimetres focal length, and the other a 7^ x 5 with a 

 Dallmeyer rapid rectilinear lens. The trail recorded by 

 the latter instrument falls so near the edge of the plate that 

 the image is somewhat out of focus ; but on the other 

 plate, although it is also near the edge, the image is very 

 sharp and clear. From an examination of this plate, the 

 following particulars have been obtained : — The path of the 

 meteor extends nearly 9° in the constellation of Camelopardus, 

 and a comparison with Cottam's star chart shows that the co- 

 ordinates of the points of appearance and disappearance were, 

 according to the photographic plate, R.A. 4h. 53m. Decl. -f 65^ 

 25', and R.A. 5h. 32m. Decl. + 66° 15'. The actual visible 

 length of trail must have been much longer than this, although the 

 lens and plates used were both very rapid. It may be mentioned 

 that the most dense part of the trail was equal in intensity to 

 that given by the image of /8 Camelopardus (4th mag.) after ap 

 exposure of fifty-five minutes (11.20 p.m. to 12.15 a.m.). 



The trail commences by being very faint, gradually increasing 

 in density ; it then fades off a little, and again becomes more 

 dense for a short period of time. After another interval it 

 becomes very dense, corresponding in this respect with the 

 image of j8 Camelopardus. Again it becomes feeble for some 

 distance on the plate with one minor condensation, and then 

 suddenly there is an abrupt increase in density, after which it 

 gradually fades away, and is no longer visible. 



The path traversed lay nearly half-way between the stars 739 

 and 780, and passes a little to the south of o Camelopardus. 

 The meteor was evidently a true Perseid, the trail, when pro- 

 duced backwards, lying slightly to the south of ij Persei. 



In conclusion, it may be added that the camera was set so 

 that 7j Persei should fall in the centre of the plate, the instru- 

 ment being mounted on the object-glass end of the Kensington 

 lo-inch equatorial. The exposure lasted from iih. 20m. p.m. 

 to I2h. 15m. a.m. W. J. S. Lockyer. 



X-Ray Tubes. 



These tubes when very highly exhausted become capricious ; 

 at times they will do good work, while at other times, and with- 

 out any known cause, they refuse to illuminate. 



In my endeavour to learn by experiment, I found that when 

 playing the electricity upon and round the outer surface of the 

 kathode end of the tube, it is quite possible to obtain 

 sparks between the kathode wire and the inner surface of the 

 glass. With each such spark the otherwise obstinate tube is 

 momentarily illuminated ; evidently the spark is owing to charges 

 induced on the inner surfaces of the tube. 



This led me to coat the kathode end of the tube with tinfoil, 

 leaving about a J-inch gap between the tinfoil and the kathode 

 terminal of the tube ; the behaviour of the tube is now much 

 affected— formerly it was uncertain when used with a 6-inch 

 spark- length — and required frequently heating. With the tin- 

 foil coating the tubes illuminate with certainty and with a much 

 shorter spark-length. In fact I can now easily, and well, 

 illuminate a highly-exhausted tube with an influence machine 

 which has 17-inch plates. James Wimshurst. 



