284 



NA TURE 



\A71g. 13-1874 



form which will not be considered antiquated. This is 

 far from the case in a work like the one we are now 

 noticing. The spirit of biological thought changes as 

 rapidly as fresh facts accumulate. The introduction of an 

 all-embracing hypothesis, like that of evolution, shakes 

 previously accepted theories to the foundation ; long- 

 known facts are looked at in quite a different aspect to 

 that in which they were received before its introduction, 

 and their relative value is differently estimated. 



Hovv then can it be expected that a zoological work, origi- 

 nally written when Cuvier's celebrated "Regne Animal" 

 was the latest te.\t-book on the subject, could be so modi- 

 tied by an editor, however able, as to make it at all a 

 representative of the present state of biological know- 

 ledge ? To do so the article on the " Pacliydctnnata, an 

 order of Mammiferous quadrupeds distinguished by the 

 thickness of their skins," would have to be removec^; 

 that on each of its component genera re-written, and the 

 word itself obliterated from the whole work. A similar 

 operation would have to be performed on many of the 

 larger orders ; and to such an extent would this process 

 have to be carried on, that it would soon become doubtful 

 whether a new work instead of a fresh edition would not 

 be the more economical as well as the more useful. 



This being the case, we are not surprised when we find 

 that nothing more is said of the affinities of the Echidna 

 than that " it has the external coating and general ap- 

 pearance of the porcupine, with the mouth and peculiar 

 generic characters of the ant-eaters ; " whilst the word 

 " monotreme" is only mentioned in the second supplement. 

 In hke manner we notice that the Dugong and Manatee 

 are said to rank among the Cetacea ; whilst the Sirenia are 

 omitted except in the appendix. The word " Chevrotaia " 

 refers us to "Musk Deer," thus perpetuating the well, 

 known error ; and, on finding it, we are told that there is 

 a Javanese Musk deer {Moschus javaiiicus) rather larger 

 than a full-sized hare, at the same time that " there are 

 other musk deer, which are very small, and to which the 

 general term of CJicvrotains is given ; they are inhabit- 

 ants of Java, Sumatra, Ceylon, and Southern India." The 

 genus " Ammocetes " has not been removed, and is still 

 said to be " a genus of Chondropterygious fishes, allied 

 to the lampreys," instead of the young of the lamprey, 

 which it has for some time been known to be. 



The creatures most fully treated of are the birds, the best 

 known of which are described with fair completeness, with 

 extracts from the works of Mr. Gould and other observant 

 naturalists, as to their habits and coloration. We do not 

 know why the Poe Honey-eater {Prosthaitadtra coiicin- 

 iiatd) is described both under its English and Latin name, 

 in the same way that it is difficult to account for the 

 Orycteropus and the lady-bird being each repi-esented 

 twice by woodcuts. 



Several of the original articles are lacking in important 

 detail. Of the Ammonite and Orthoceras it is only said 

 that they are genera of fossil shells, which leaves their 

 affinities unnecessarily vague. So there is not much to be 

 learnt from the observation that Numinulites are " small 

 round fossil shells, which in various parts of the world 

 are found in immense numbers." 



Mr. Holdsworth adds an extra supplement, which con- 

 tains much useful information of recent origin. It in- 

 cludes an account of the breeding of the hippopotamus 



and of the Sumatran rhinoceros, specimens of both of 

 which have been born in this country during the last two 

 or three years. The Liberian, or Lesser Hippopotamus, is 

 also described, as is the new Bird of Paradise Drcpan- 

 oniis d'albvr/ist, obtained from New Guinea by Signor 

 d'Albertis, and named by Mr. Sclater. An account is 

 also given of the nesting of the crocodile in Ceylon, and 

 of the incubation of the python. 



This second supplement also adds to the pala:onto- 

 logical information contained in the first, by giving a 

 description of the Dinoccras mirabilis of Prof Marsh, 

 from Colorado ; of Archceopteryx lithograpliica, of the 

 other Odontornithes, and of Odontopteryx talipoica. 



Notwithstanding the imperfections we have pointed 

 out, there is much information to be obtained from this 

 work, and which can be obtained from it more easily than 

 from any other, on account of its being arranged al- 

 phabetically, and from the succinctness of the articles. 



OUR BOOK SHELF 



The Amateur's Photographie Guide Book. Being a com- 

 plete Resume of the most useful Dry and Wet Collodion 

 Processes, especially for the use of Amateurs. By W. 

 J. Stillman. (London : C. D. Smith and Co.) 

 Although we already possess numerous books of this 

 class, the present little volume will doubtless meet with 

 a welcome from amateur photographers, coming as it dots 

 from the pen of one well known to be a thoroughly prac- 

 tical worker. The book is small (numbering only 92 pp.), 

 but contains sufficient information for those who desire 

 to master the dry and wet collodion processes. Indcjd, 

 more pretentious works on photography which have come 

 under our notice contain a large amount of what we are 

 inclined to regard as utterly superfluous matter, and it 

 is, moreover, refreshing to open a " Guide " which is nut 

 made a medium for some dealer's price-catalogue. The 

 present work consists of three chapters and six appen- 

 dices. The first chapter treats of cameras, and describes 

 the process of taking pictures by the dry-plate method ; 

 some useful hints will be found in this chapter by outdoor 

 photographers. The second chapter describes the ordinary 

 wet collodion process — a process which has been so often 

 described before, that Mr. Stillman has little to add by way 

 of novelty ; while the third chapter is devoted to positive 

 prints. In the appendices we have special remarks on 

 baths and bath solutions, on cleaning plates, on deve- 

 lopers, on dry processes, &c. On this last subject, by the 

 way, we notice that the decimal point has been omitted from 

 several of the numbers in the formula;, and although these 

 are doubtless typographical errors, the figures as they 

 stand will be apt to mislead beginners : " Sulphuric acid 

 1S40," for instance, would at first sight lead the uninitiated 

 into the belief that an acid in bottle since this date was 

 necessary for success in making pyroxyline, whereas the 

 author only means an acid of sp. gr. ry4o. 



On consulting books on practical photography, any- 

 one who pretends to any knowledge of chemical science 

 cannot fail to be struck by the empiricism of the various 

 formuhu proposed, and a feeling akin to regret is expe- 

 rienced on reflecting that this fascinating and useful art 

 has reached its prescit state of perfection by processes 

 which have been essentially methods of trial and error. 

 The large numbers of practitioners, both professional and 

 amateur, now engaged with this subject ought surely to 

 produce from their ranks investigators willing, as we 

 know they are able, to take up the purely scientific aspect 

 of the subject. The harvest reaped by such an inves- 

 tigator would surely repay him, for we are of opinion that 

 in the theory of the sensitive film lie hid some of the 

 fundamental truths of molecular physics. R, M. 



