Jan. 30, 1890] 



NATURE 



293 



■order has not in every case been adhered to, the main 

 idea and its subsequent development being frequently 

 -treated together ; but the sequence of epoch-making events 

 is strictly maintained. The work is quite up to date ; 

 Avhen advisable, the author has introduced facts which 

 have only been established by recent investigations. 



The book is tastefully bound, and the illustrations are 

 numerous. The latter are varied, and embrace cuts from 

 ■ Die Zwolf Schliissel," apparatus historic and modern, 

 .ind portraits of celebrated chemists. To the reader pos- 

 sessed of some chemical knowledge the volume will be 

 most useful, and to the uninitiated its earlier chapters, at 

 <east, cannot fail to be inviting. 



LUMINOUS ORGANISMS. 

 I^es Animaux et les V^getaux Luviineux. Par Henri 

 Gadeau de Kerville. (Paris : J. B. Bailliere et fils, 

 1890.) 



THIS little book is a semi-popular summary of what is 

 known in regard to the photogenous structures of 

 the various kinds of luminous animals and plants, com- 

 monly (but improperly, as the author points out) known 

 •as phosphorescent. As it is on the whole fairly complete 

 and accurate, being based largely upon the important 

 researches of Panceri, Sars, R. Dubois, Emery, and 

 •others, it will probably be useful not only to amateurs, 

 but also to students who wish to get a general knowledge 

 •of the range in organic nature of light-producing forms, 

 and of the more important investigations on the subject 

 which have been made since the days of Aristotle and 

 Pliny. 



Although the title-page of this book bears the date 

 1890, the important discovery by Giard, in September 

 last, of luminosity in Amphipods which is due to an 

 infectious disease is, it may be supposed, too recent to 

 have been included — at any rate, it is not referred to. 



After a short historical rdsuvie, the first half of the 

 work (170 pages) is occupied by a systematic account of 

 those plants and animals which are luminous, commencing 

 with the plants and then working up through the animal 

 series from Protozoa to Vertebrata. More animals than 

 plants are photogenous, and most of these are marine. 

 Few observations have been made upon freshwater forms, 

 and none are known from brackish water. M. Gadeau 

 de Kerville takes care to point out, what is undoubtedly 

 the case, that many supposed instances of luminosity, 

 <;specially in dead animals or in the neighbourhood of 

 harbours, &c., where there is much decaying organic 

 matter, are due, not to any " phosphorescence " of the 

 animal observed glowing, but to the presence of luminous 

 Bacteria on the surface, in mucus, or in the tissues. 

 Several species of light-producing micro-organisms {jBa- 

 cilH and Micrococci) are already known, and the list will 

 probably be largely added to in the future. It is, how- 

 ever, an excess of caution to doubt the claim of Ceraiium 

 {Peridifiium) to be placed amongst photogenous genera, 

 as two or three of the species appear to be responsible 

 for a good deal of the " phosphorescence of the sea " 

 around our western coasts in autumn— a phenomenon 

 which is usually attributed even by naturalists to Nocti- 

 luca viiliaris, although at such times it often happens 

 that not a single Noctiluca is caught by the townet ! 



The well-known observations and experiments of Pan- 

 ceri on Pennatiila and other forms are given, and the 

 figures reproduced, and it will no doubt be useful to many 

 to have the information obtained by various investi- 

 gators thus collected into one volume. On p. 83 is given 

 an observation by Quatrefages upon certain luminous 

 Talitri (Amphipod Crustaceans) on the beach, which he 

 supposed had derived their luminosity from contact with 

 Noctiluca. Is it not more probable that, like Giard's 

 diseased Amphipods at Wimereux (which, by the way, 

 have turned up lately at Jersey, and will probably be 

 found to be widely spread), they were infested by a 

 photogenous microbe ? 



In connection with the remarkable " luminous globules " 

 of some Schizopods {Euphausia, Nyctiphanes, &c.), M. 

 Gadeau de Kerville suggests that these organs are light- 

 perceiving, as well as light-producing, and that, therefore, 

 the old designation of " accessory eyes" was not impro- 

 perly applied. This view is supported by several ob- 

 served cases where the true eyes of higher Crustacea 

 were luminous ; but it should be remembered that it is 

 entirely opposed to the matured opinion given by G. O. 

 Sars in his Report on the Challenger Schizopods. 



Chapter xiii. is devoted to an account of the anatomy 

 and physiology of the photogenous organs, in which, 

 however, little of importance is added to what was 

 given in the preceding part of the book. The author 

 adopts the view of Dubois (founded upon experiments on 

 Pholas dactyliis made at the Roscoff Laboratory), that in 

 all cases the luminosity is a purely physico-chemical phe- 

 nomenon, and is dependent on the presence of two sub- 

 stances — the one ijuciferine) soluble in water and obtain- 

 able in the crystalline state, the other (lucife'rase) a soluble 

 ferment (like diastase) — which must be brought in contact 

 in order that light may be produced. This seems going 

 further than our present knowledge really warrants. The 

 light-producing organisms and organs are so varied that 

 it is possible that the causes of the luminosity may be 

 manifold ; and, at any rate in the higher forms, the bring- 

 ing together of the lucifirine and luciferase must be 

 under the direct control of the nervous system, as the 

 production of light is a reflex, perhaps in some cases a 

 voluntary, action. 



In a short chapter, entitled " Philosophie naturelle," 

 the author considers, from the evolution stand-point, such 

 questions as the origin of luminosity, the reason why 

 only relatively small numbers of animals and plants are 

 luminous, why the majority of luminous animals are 

 marine, &c. ; but for a discussion of these points, and 

 also of the various uses (both to animals and to man) 

 which the luminosity may have, reference must be made 

 to the book itself, which, although some of the illus- 

 trations are poor, and there is unnecessary repetition 

 and verbosity in the text, forms a readable and useful 

 introduction to a very interesting and important subject. 



W. A. Herdman. 



OUR BOOK SHELF. 



The Chemistry of Photography. By R. Meldola, F.R.S. 

 (London ; Macmillan and Co., 1889.) 



This work is well worthy of study by serious devotees of 

 photography. It enters, as its title indicates, into the che- 

 mistry of photography, and that in a very thorough and 



