November 3, 1892] 



NATURE 



3 



The work is divided into four parts, of which the 

 first, entitled "The Everyday Life of Animals," deals with 

 the wealth of life, the web of life, the struggle of life, the 

 shifts for a living, the social life of animals, the 

 domestic life of animals, and the industries of animals. 

 The second part, on " The Powers of Life," contributed 

 by Mr. Norman Wyld, treats of vitality, the divided 

 labours of the body, and instinct. The third par 

 describes " The Forms of Animal Life " and includes 

 chapters on the life-history of animals, and their past 

 history as read in the geological record. The fourth 

 and last part treats of " The Evolution of Animal Life " 

 and, besides a discussion of the influence of habits and 

 surroundings, and of heredity, gives a sketch of the 

 evolution of evolution theories. Appendices on the 

 relation of animal life to human life, and on some of the 

 best books on animal life bring the work to a conclusion. 



The general arrangement of the subject-matter is, as will 

 be seen by the above summary, well and carefully thought 

 out, and the facts given in elucidation of the varied ten- 

 dencies of organic development are skilfully marshalled 

 and are derived from the most trustworthy sources. The 

 information given is therefore accurate and up to date. 

 The only suggestion we have to offer in this connection 

 is that a little more selective elimination might have been 

 exercised. Some facts are given in so terse and con- 

 densed a form that no one but a zoologist could appre- 

 ciate their value. If a considerable number of these had 

 been struck out and the space thus gained had been 

 utilized in expanding those that remained, the Extensionee 

 would have been the gainer. " The Zoological Summary 

 of the Animal Kingdom" (pp. 210-272) might by some 

 such process have been replaced by a sketch with more 

 life and go in it. As it stands it will, by many readers, be 

 gracefully skipped. 



In such a work style is an important element. Here 

 Mr. Thomson is often exceedingly happy. He has ima- 

 gination and a feeling for the poetic aspect of nature. 

 But his imagination and poetry need at times just a little 

 chastening. When he tells us that in birds " the breath- 

 ing powers are perfected and economized by a set of bal- 

 loons around the lu?tgs,^' and that their brains " are not 

 wrinkled zuiih thought like that of mammals " ; when he 

 speaks of the sponge as "« Venice-like city of cells'" ; 

 when he describes the ciliated cells of the windpipe 

 as " lashed cells," or the embryonic membranes as ^^ birth- 

 robes^' and when he says that in ponds subject to drought 

 the organism often " sweats off a protective sheath which 

 is not a shroud, and waits until the rain refreshes the 

 pools"; in these and sundry other cases of which these 

 are samples, one may question whether the expressions 

 which we have underlined are justified either by special 

 elegancy or by real helpfulness to a beginner. And this 

 we say in no spirit of hypercriticism, but as desirous of 

 aiding the author in what is by no means an easy 

 task. 



Somewhat deeper would be our criticism of sundry ex- 

 pressions which are of essentially human implication and 

 which in our opinion should not lightly be applied to 

 animal activities. Much is said of the " love " of animals 

 for their mates when some such phrase as " sexual 

 appetence " would be more appropriate. For example, 

 concerning ants we read : — " After this midsummer day's 

 NO. I 20 1, VOL. 47] 



delight of love death awaits many, and sometimes most." 

 And in the analysis of the forms of struggle for existence, 

 we have the " struggle between rivals in love." Again, 

 of the cuckoo it is said that, "in spite of the poets, the 

 note of this 'blessed bird' must be regarded as sugges- 

 tive of sin " I And again, " It is not quite correct to say 

 that the cuckoo-mother is immoral because" she shirks 

 the duties of maternity ; it is rather that she puts her 

 young out to nurse because she is immoral." It is true 

 that Mr. Thomson adds this footnote : — " The student 

 will notice that I have occasionally used words which 

 are not strictly accurate. I may therefore say definitely 

 that I do not believe that we are warranted in crediting 

 animals with moral, aesthetic, or, indeed, any concep- 

 tions." We are glad to be thus assured. But why im- 

 plant notions in the text which have to be eradicated in 

 a footnote "i Does not Mr. Thomson know how easy it 

 is to sow tares and how difficult to root them out ? 



Mr. Norman Wyld's chapter on " Instinct " is short, 

 but quite to the point. We hope that he may further 

 observe and experiment in the field of comparative 

 psychology, for he is fully alive to the peculiar difficulties 

 of the subject, and there is a wide field before him in 

 which the scientific workers are none too many. In 

 criticizing Mr. Lloyd Morgan's definition of instincts as 

 "oft-recurring or essential to the continuance of the 

 species," Mr. Wyld says : — " This is not quite satis- 

 factory, for many actions that are instinctive are not oft- 

 recurring, and many are not necessary to the preserva- 

 tion of the species." He does not show that there are 

 any such actions which are neither the one nor the other. 

 We have reason for supposing that he understood 

 Mr. Lloyd Morgan to say that instinctive actions were 

 " oft-recurring and essential to the continuance of the 

 species." But this he did not say. 



In conclusion we may repeat that " The Study of Ani- 

 mal Life," though by no means faultless, may be recommen- 

 ded to Extension students and the general reader as, in the 

 main, accurate, readable, and suggestive. 



C. Ll. M. 



VECTOR ALGEBRA. 



Principles of the Algebra of Vectors. By A. Macfar- 



lane, M.A., D.Sc, LL.D., F.R.S.Edin., Professor of 



Physics in the University of Texas. Reprint from the 



Proceedings of the American Association for the 



Advancement of Science, Vol. XL., 1891, pp. 65-117. 



(Salem Press, Salem, Mass., 1891). 



'""T'HIS is a very suggestive contribution to the founda- 



J- tions of the Algebra of Vectors as recently so 



strongly advocated in America by Prof. Willard Gibbs, 



and in this country by Mr. Oliver Heaviside. 



The extensive use of quaternions among physicists 

 has been prevented by the fact that the meaning of a 

 product of vectors has been made to depend on the 

 use of a vector as a quadrantal versor, and by the fact 

 that this method leads to the square of a vector being 

 negative. The advocates of the new algebra define a 

 product of vectors independently and in such way that 

 the square of a vector is positive. Rotations are ex- 

 pressed by means of dyadics, or ratios between vectors 



