r 



November 7, 1895] 



NATURE 



■written an original and stimulating book, which should 

 1)6 studied, not only by professed mathematicians, but by 

 intelligent school teachers. Such a work ought to do 

 much towards replacing the soul-destroying routine of 

 •ordinary school arithmetic by something of a really 

 educative character. 



In conclusion, we would ask the reader to turn' to the 

 chapter on the metric system, which contains in the com- 

 pass of about a dozen pages all the " commercial arith- 

 metic" which a French schoolboy has to learn. It seems 

 impossible that any one, after reading this chapter, can 

 refrain from asking himself how it is that the English 

 nation persists in refusing to adopt a system which is as 

 easy to learn as it is convenient to use, and which, as the 

 experience of France has sufficiently shown, could be 

 prescribed by the State without the risk of any, save the 

 most transient, disturbance of trade or exchange. But 

 -vve are a practical people, and the metric system was in- 

 vented by " theoreticians " ; therefore, we suppose, nails 

 and perches and pennyweights will be with us to the end 

 of time. G. B. M. 



THE STRUCTURE AND LIFE OF BIRDS. 

 The Structure and Life of Birds. By F. W. Headley, 



M.A., F.Z.S., Assistant Master at Haileybury College. 



8vo. Pp. XX. + 412, with seventy-eight illustrations. 



(London : Macmillan and Co., 1895.) 

 *T^HE author in his preface intimates that " the aim of 

 -L this book is an ambitious one," namely, " to give 

 •good evidence of the development of birds from reptilian 

 .ancestors. . . . and [among other subjects] to make 

 clear the main principles of their noble accomplishment, 

 flight." To the former of these aims Mr. Headley de- 

 votes his first five chapters, comparing the differences 

 and resemblances observable in the skeleton and the 

 internal structure of birds and reptiles, and the "ances- 

 tral peculiarities" that, having "survived all change of 

 habit," mark their relationship. He then discusses the 

 processes of life that go on within the bird, and make it 

 so different from its lethargic reptilian ancestors, giving a 

 description of the anatomical structure and physiological 

 action of its chief organs. The following paragraph, 

 from the description of the heart and circulation, will 

 exemplify Mr. Headley's style and method of exposi- 

 tion : — 



" The heart is a force-pump, which drives the blood to all 

 parts of the body, and when it returns impure and loaded 

 with used-up material, sends it to the lungs to be purified, 

 after which it is despatched all over the body again. On 

 the voyage much of it passes through the kidneys, which 

 lielp the lungs to purge it of the waste of the tissues. The 

 essentials of an efficient heart are that it should be strong, 

 and that it should keep the pure blood separate from the 

 impure. These two essentials are found combined in the 

 hearts of mammals and birds. They are strong muscles ; 

 that part at least of them which forces the blood through 

 the arteries is remarkable for its strong thick walls. And, 

 thanks to the perfection of the machinery, the blood 

 which has been purified in the lungs is never mixed with 

 the impure blood which is coming from the body. The 

 heart is divided into right and left chambers by a division 

 through which there are no doorways. The right and 

 fi chambers are each divided into two, but there are 

 ■cnings from the upper into the lower, which may be 



NO, 1358, VOL. 53] 



closed by valves. The two lower chambers are called 

 ventricles, and the two upper ones auricles." 



A long chapter is next given to flight, one of the 

 main subjects of the book ; the machinery by which flight 

 is accomplished, and the principles underlying the action 

 of its complicated mechanism, with the extraneous aids 

 the bird avails itself of to effect that purpose. Towards 

 a solution of this difficult subject, on which, as the author 

 remarks, " however much is learnt, a great deal more 

 remains to be learned," he has contributed some original 

 observations and experiments, for which we refer the 

 reader to the book itself A condensed but clear 

 account of the bird's embryology and its subsequent life- 

 history occupies several succeeding chapters. After this 

 the book deals principally with colour and song, instinct 

 and reason, migration and the principles of classification. 



There is one statement made by the author, in speaking 

 of the pneumaticity of the bird's bones, to which we feel 

 inclined to take exception. Mr. Headley says on p. 107 : 

 " The hornbills, which according to good observers are 

 very poor flyers, are as pneumatic [as to their bones] 

 as any birds, or, perhaps, more so." The present writer's 

 experience of hornbills in their native state extends to 

 many species of several genera, among them the largest 

 and heaviest of them all, the great solid-headed Buceros 

 galeatus. Many of these birds, which may be seen — 

 and the rush of their expansive wings can be heard long 

 before that — constantly travelling at a great speed high 

 over the tall virgin forests, and be watched by eye and 

 ear for miles after they have passed over the observer, 

 can scarcely, in his estimation, be accurately designated 

 " poor flyers." They may not take such extended flights 

 as birds on migration do, but they make journeys of 

 considerable length ; while in the tops of the highest 

 trees, in quest of their food, they are quite as active and 

 nimbly expert as those excellent flyers, the pigeons, which 

 share with them their raids on the giant Urostigmas. 



The volume before us presents httle to take exception 

 to, and it will be generally conceded that Mr. Headley 

 has succeeded well in the aims he set before himself. He 

 has produced a very instructive and thoroughly scientific 

 book expressed in popular language, and one that will 

 undoubtedly " prove useful," as he hopes it may, " to 

 lovers of birds " ; and, from the clear and concise manner 

 in which the story of the bird's pedigree and life-history 

 is narrated, it will be specially welcome to those of them 

 who have not had the advantage of a scientific training 

 in the subject ; while it can scarcely fail to attract many 

 of its readers, on the outlook for a spare-time occupa- 

 tion, to the study of ornithology, on which it will start 

 them with a trustworthy groundwork. 



OUR BOOK SHELF. 



Fern Growing. Fifty year^ Experience in Crossing ana 



Cultivation., with a List of the most Important Varieties, 



and a History of the Discovery of Multiple Parentage., 



&^c. By E. J. Lowe, F.R.S., F.L.S., &c. (London : 



John C. Nimmo, 1895.) 



Mr. Lowe's name is so v.ell known in connection with 



the production of hybrid ferns, that his book will be 



opened with interest by all those to whom the cultivation 



of these plants in any way appeals. But we must confess 



that the book falls somewhat short of our expectations 



