620 



NATURE 



[October 25, 1900 



Field Class provide teachers in London or the neighbour- 

 hood with exceptional opportunities for acquiring a 

 knowledge of the significance of the geological structures 

 and formations in the home counties, and Mr. Cowham's 

 book will show them how the facts can usefully be applied 

 to school excursions. 



Air, Water and Food. By Ellen H. Richards and 

 Alpheus G. Woodman. Pp. 226. (London : Chapman 

 and Hall, Ltd. New York : John Wiley and Sons, 

 1900.) 

 Of the many volumes which have been written on these 

 subjects, there are few which, in the opinion of the writer, 

 can be more safely recommended to the student of sani- 

 tary science. Each of the three subjects is introduced 

 and fairly discussed in language which is clear, trenchant 

 and concise. 



The authors are, moreover, no mere theorists, but 

 describe the operations of the laboratory in a business- 

 like fashion which leaves no doubt about their practical 

 knowledge. The diagrams are more successful as illus- 

 trations than the photographs, in which, as frequently 

 happens, the glass apparatus has such an ill-defined and 

 ghost-like appearance as to be unrecognisable by the un- 

 professional eye. In other respects the book is well 

 got up. J. B C. 



Elementary Physics and Chemistry, ii., iii. By R. A. 

 Gregory and A. T. Simmons. Second stage, pp. vi -f 

 140 ; third stage, pp. vi + 114. (London : Macmillan 

 and Co., Ltd., 1900.) 

 These two volumes complete a work of three parts, 

 consisting of a course of experimental illustration of the 

 elementary principles of chemistry and physics. The 

 syllabus of subjects considered is based on the new 

 Code issued by the Education Department, but the 

 descriptions are by no means confined to it. The subject- 

 matter is arranged in the form of a succession of separate 

 gradated lessons, each consisting of description of appa- 

 ratus, method of conducting experiment, results obtained 

 and the reasons for them, short summary, and a set of 

 exercises. The books thus arranged seem especially 

 valuable to teachers having to give a comprehensive 

 course in a definite number of lessons — in Evening Con- 

 tinuation Schools, for instance — as the whole work to be 

 gone through may be at once divided into sections. 

 Numerous excellent illustrations add considerably to the 

 utility of the volumes. C. P. B. 



Principes U Hygiene Coloniale. Par Le Dr. Georges 

 Treille. Pp. iv -\- 272. (Paris : Georges Carre et C. 

 Naud, 1899.) 

 This useful little volume is addressed particularly to 

 those who wish to inform themselves of the physical 

 conditions of life in the tropics with a view to living there, 

 and to those who have an indirect interest in tropical 

 regions. The earlier portion of the volume deals with 

 tropical climatology in general, and in particular with 

 the climatology of the French colonies. A chapter is 

 devoted to considering the action of the climate on bodily 

 functions. The latter portion deals with public and 

 domestic hygiene. In the discussion on European habita- 

 tions in the tropics, one would have wished to see more 

 stress laid on the importance of Europeans living apart 

 from the natives — a custom which has been so universally 

 adopted in India, and which no doubt accounts to a large 

 extent for the comparative freedom of Europeans from 

 malaria in that country. 



We fully endorse the indictment of the use of alcohol 

 specially in the form of absinthe, but we should have 

 liked to see more information on measures to be taken 

 to ensure a supply of good water for domestic purposes, 



C. B. S. 



NO. 1617, VOL. 62] 



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. ^ 



Genesis of the Vertebrate Column. 



In the review of " The Foundations of Zoology," by Prof, 

 W. Keith Brooks, which was contained in the last number of 

 Nature, the reviewer quotes from him the following sentence : — 

 " Herbert Spencer tells us that segmentation of the backbone is 

 the inherited effect of fractures caused by bending." 



Before the reader accepts this version of my view, he would do 

 well to read §257 of " The Principles of Biology." The simplest 

 expression of that view is contained in the criticism of Prof. 

 Owen's " Theory of the Vertebrate Skeleton," originally pub- 

 lished by me in the British and Foreign Chirurgical Re- 

 view for 1858, and now appended to "The Principles of 

 Biology." The sentence setting it forth runs thus : — 



"The production of a higher, more powerful, more active 

 creature of the same type, by whatever method it is conceived to 

 have taken place, involved a change in the notochordal structure. 

 Greater muscular endowm.ents presupposed a firmer internal 

 fulcrum — a less yielding central axis. On the other hand, for 

 the central axis to have become firmer while remaining con- 

 tinuous, would have entailed a stiffness incompatible with the 

 creature's movements. Hence, increasing density of the central 

 axis necessarily went hand in hand with its segmentation ; for 

 strength, ossification was required ; for flexibility, division into 

 parts." 



There is here no mention or thought of "fracture" — no im- 

 plication of a dense part formed and then broken, but the 

 implication of dense matter being deposited in successive 

 separate portions, in such way as to fulfil the two requirements of 

 strength and flexibility. Herbert Spencer. 



Brighton, October 21. 



Albinism and Natural Selection, 



A CASE of partial albinism in fishes which has recently come 

 under my notice is likely to be of general interest from the 

 evidence it apparently affords of the value of the normal specific 

 coloration of predaceous fishes, and of the serious disadvantage 

 of conspicuous abnormalities. 



A white-skinned specimen of the common hake [Merluccius 

 ;«£r/M^««j-, L.) was trawled in the Bristol Channel last week 

 amongst a catch of normal hake, and was sent to me from 

 Milford immediately on landing, owing to the fishermen's 

 impression that it belonged to some rare species unknown to 

 them. 



It was, however, perfectly normal in all respects except its 

 remarkable leanness and the absence of all pigmentation from 

 the external skin and the inner lining of the buccal cavity and 

 gill-covers. The pigmentation of the retina and peritoneum 

 was normal. 



In a normal hake there is a profuse black pigmentation over 

 the upper part of the body, as well as over the inside of the 

 mouth and gill-covers. ^The general appearance of a normal 

 hake is consequently dusky ; that of the abnormal specimen was 

 white. 



The lean and emaciated condition of the white hake was very 

 striking, especially in the head region, where not only the bony 

 ridges of the skull and cheeks projected sharply beneath the 

 thin layer of skin, but even the lines of sculpture of the super- 

 ficial bones were plainly recognisable. In a normal hake, of 

 approximately equal length, with which I compared the 

 specimen, these details were quite invisible, and the bony ridges 

 were rounded off or hidden by the plumpness of the integument. 

 In girth and weight the albino was far inferior to the normally 

 pigmented fish. The albino measured 26I ins. in length to the 

 base of the caudal fin, and b\ ins. in length of head (from snout 

 to opercular spine). Its girth round the back of the head was 9 

 ins., and just behind the loth anal finray 9I ins. The normal 

 hake measured ^^\ ins. in length, and had the same length of 

 head as the albino. Its girth in the same two regions was 1O5 

 ins. and lo^ ins. respectively. The albino weighed 4 lb. 5 oz., 

 the normal hake 5 lb. 9^ oz., both fish being gutted in the same 

 way. 



