174 



NATURE 



[October 6, 192 1 



for many patients have not hitherto been 



met." 



The last section of the volume is an ad- 

 mirable summary of the subject. We hope 

 it will be read by, and give fresh heart to, 

 all engaged in national tuberculosis work. 

 We wish it could be brought home also 

 to the hearts and minds of central and local 

 governing bodies, who, unfortunately, at the 

 present time, are engaged in whittling down 

 essential public health activities, which is any- 

 thing but economy of the welfare of the Common- 

 wealth, on which efficiency depends. 



Physics and Chemistiy of Bioluminescence. 



The Nature of Animal Light. By Prof. E. N. 

 Harvey. (Monographs on Experimental Bio- 

 logy.) Pp. X-M82. (Philadelphia and Lon- 

 don: J. B. Lippincott Co., 1920.) 105. 6d. net. 

 BIOLUMINESCENCE— that is, the production 

 of light by animals and plants — is a phe- 

 nomenon which has excited wonder in the layman 

 and given rise to many investigations on the part 

 of the man of science. Since the results of these 

 investigations, many of them of a purely qualita- 

 tive nature, are widely scattered in the literature 

 of various countries and not always readily access- 

 ible, the author has rendered a distinct service In 

 collating the various facts and presenting them to 

 the scientific public as a connected whole. The 

 biological aspect Is referred to but briefly, In a 

 chapter on the structure of the luminous organs, 

 the main portion of the book dealing with the 

 physical characteristics of animal light and the 

 chemical processes underlying Its production. The 

 study of bioluminescence Is another Instance of 

 the application of physics and chemistry to bio- 

 logical and physiological problems; the author's 

 treatment is clear and, so far as the present state 

 of our knowledge Is concerned, convincing; It 

 shows, moreover, that he has full command of 

 the cognate sciences. 



After providing. In the first two chapters, 

 an account of the physical phenomena of 

 luminescence and incandescence. In which, 

 especially, the various kinds of luminescence are 

 adequately discussed; a detailed description is 

 given of the results obtained In the physical inves- 

 tigations of the nature of animal light. It is in 

 such physical Investigations that most progress 

 of a definite nature seems to have been made. 

 Exact quantitative measurements have established 

 that the light emitted is In no way different from 

 ordinary light, except In Intensity and spectral 

 extent; It Is all visible light, containing no Infra- 

 NO. 2710, VOL. 108] 



red or ultra-violet radiations or rays which are 

 capable of penetrating opaque objects. Like 



ordinary light, it will cause fluorescence and 

 phosphorescence of substances, aff"ect a photo- 

 graphic plate, cause marked heliotropism of seed- 

 lings, and stimulate the formation of chlorophyll. 

 The efficiency ( = visible radiation x visual sen- 

 sibility h- total radiation) of the firefly as an 

 illuminant seems to be of the order of 96 per 

 cent. — that Is, Immeasurably superior to any arti- 

 ficial source of light. The light, however, sup- 

 posing it could be put to use, would not be suit- 

 able for artificial illumination, since all objects 

 would appear a nearly uniform green hue. 

 Although the light of the firefly is the most effi- 

 cient known, so far as amount of light for ex- 

 penditure of energy Is concerned, it has been pro- 

 duced at the inevitable expense of range of colour. 

 The last three chapters deal with the chemistry 

 of light production and the dynamics of lumines- 

 cence. As is only to be expected from the nature 

 of the case, the chemistry of bioluminescence has 

 not yet been placed on a basis as satisfactory as 

 the physics thereof ; the evidence, as yet, is 

 mainly of a qualitative nature. It seems to be 

 established that. In at least three groups of 

 animals, luminescence Is due to the interaction of 

 two substances, luciferln and luciferase, In the 

 presence of water and oxygen, Luciferase is a 

 protein, all Its properties agreeing with those of 

 the albumins, and may be regarded as an enzyme ; 

 luciferln has many properties In common with 

 the proteoses and peptones, but its chemical 

 nature still remains to be decided. The stage to 

 which our knowledge of the dynamics of animal 

 luminescence has advanced may be Indicated by 

 the fact that the author only commits himself to the 

 statement that " perhaps the reaction takes place 

 in two stages," a compound luciferin-lucif erase 

 being first formed and then undergoing oxidation. 

 A valuable bibliography is given at the end of 

 the book, which is printed in clear type and well 

 supplied with illustrations and diagrams. 



T. S. P. 



Our Bookshelf. 



The Arithmetic of the Decimal System. By Dr. J. 

 Cusack. Pp. xvI + 492. (With answers.) 

 (London: Macmillan and Co., Ltd., 1920.) 65. 

 Dr. Cusack is a firm believer in the decimal 

 system, and there can be no doubt that he speaks 

 with some authority, in view of the great experi- 

 ence he has enjoyed of teaching arithmetic and 

 other branches of a business training to all classes 

 of pupils. Many have argued theoretically about 

 the educational and commercial advantages of a 



