December 6, 1900] 



NATURE 



XI'J 



The part which is devoted to the hver opens with a 

 comparison of the structure of that with other glands, 

 and is followed by a historical account of the discovery 

 of the bile canaliculi, which furnishes an excellent example 

 of the value of applying the methods of physiology to the 

 elucidation of structure. The treatment of the liver 

 cell alone occupies some forty pages, although this is 

 a subject which, in most text-books of histology, is con- 

 sidered to be sufficiently dealt with in as many lines. 

 Another important part of this section, not merely 

 from a morphological but also from a pathological point 

 of view, is that devoted to the connective tissue of the 

 lobules, which was originally shown by von Fleischl 

 (working with Ludwig) to be so abundant ; a fact 

 which has been confirmed and extended by several 

 observers employing modern histological methods. Like 

 its predecessors, this volume is a storehouse of informa- 

 tion upon the subjects of which it treats, and must remain 

 for many years an indispensable work of reference, not 

 only to the comparative anatomist and histologist, but 

 also to the physiologist. E. A. S. 



OUR BOOK SHELF. 



Flies Injurious to Stock. By Eleanor A. Ormerod, LL.D. 

 Pp. 80. (London : Simpkin, Marshall, Hamilton, Kent 

 and Co., Ltd., 1900.) 



Miss Eleanor A. Ormerod continues her useful work 

 of popularising the information which has been acquired 

 concerning the life-histories of injurious insects by 

 issuing, in a form accessible to all, an account of the 

 principal dipterous pests which infest stock. 



The book does not pretend to be a contribution to 

 science, for Miss Ormerod's own important observations 

 on the "Warble-fly" have been several times previously 

 published, and the rest of the work is mainly compiled 

 from various authors whose papers are duly referred to in 

 footnotes. 



The Hippoboscidae are represented by the "forest- 

 fly" and the so-called "sheep-tick," but most of the 

 book is devoted to an account of the Tabanids or " gad- 

 flies " and the CEstridae or " bot-flies," and the writer 

 tries to make clear the differences in structure and habits 

 between the members of these two families. Much 

 general ignorance exists with regard to the common 

 biting flies, and the brief account of them here given will, 

 we imagine, be particularly welcome. Considering the 

 frequency of their occurrence, remarkably little is known 

 of the early history of some of these insects, but Miss 

 Ormerod is surely in error in stating that that oi Haemato- 

 pota is unknown, for the larva has been described and 

 figured by Perris. 



The CEstridae, economically the most important family, 

 naturally come in for the fullest treatment. Errors which 

 have crept into the usual accounts of the " sheep's nostril 

 fly " are corrected. Larvae, not eggs, are laid in the 

 sheep's nostril, but though they work up into the nasal 

 passages, they never, as is often stated, reach the brain. 



A second horse bot-fly which occurs in this country, 

 Gastrophilus haemorhoidalis, might have been mentioned, 

 especially as it is more easy of detection and more sus- 

 ceptible of treatment than the common species. 



The otherwise excellent account of the "warble-fly" 

 is marred by the incorporation of a large amount of cor- 

 respondence, the gist of which might have been com- 

 pressed into a few lines. However appropriate the 

 inclusion of these letters in Miss Ormerod's original 

 papers on the subject, they seem out of place in a resume 

 such as that before us. 



LETTERS TO THE EDLTOR. 



[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. \ 



The Value of Magnetic Observatories. 



In answer to those who consider that the magnetic results 

 obtained at Kew Observatory are of little or no practical value, 

 I would offer the following remarks for their consideration. 

 The railway engine driver may run his 70 miles an hour on rails, 

 certain as to being on the risjht road, and in like manner the 

 electric tram car driver may keep in the right direction. 



The sailor, however, on the trackless ocean, has only his com- 

 pass to guide him, at best directed by that unstable magnet the 

 earth. But the earth by induction transforms his iron or steel 

 ship into a still less stable magnet, which not only disturbs the 

 compass on board but permanently reduces the value of the 

 earth's directive force on that compass by 'i or '2 of that observed 

 on land. 



Fortunately, as the knowledge of terrestrial magnetism 

 increased, men of science were gradually enabled to solve the at 

 one time knotty problem of a ship's magnetism, and the seaman 

 can now run his vessel over twenty knots an hour in safety on a 

 dark night. Without a knowledge of terrestrial magnetism, the 

 now universal iron or steel ship would have been almost an 

 impossibility, and the faster ships go the more necessary does 

 that knowledge become, to wit in the navigation of the St. 

 Lawrence and English Channel. The sailor is continually asking 

 for charts of the magnetic declination to be brought up to date ; 

 Kew and other magnetic observatories help largely in this 

 direction. 



Moreover, a theory of terrestrial magnetism is much wanted 

 which (letting alone other possibilities) would enable us to pro- 

 vide accurate charts of the magnetic elements years in advance, 

 in the same manner that the "Nautical Almanac " is prepared. 

 Hence the importance of Kew as a valuable link in the chain of 

 magnetic observatories, which has already been reduced by the 

 destruction caused by electric tramways. 



Blackheath, S. E. Ettrick W. Creak. 



Huxley's Ancestry. 



With reference to Lord Avebury's reminiscences of Huxley, 

 and the summary of his views concerning British races, it may 

 be of interest to quote Huxley's account of his own racial 

 characters, as contained in a private letter written ten years ago : 

 " My father was a Warwickshire man ; my mother came of 

 Wiltshire people. Except for being somewhat taller than the 

 average of the type, she was a typical example of the ' Iberian ' 

 variety — dark, thin, rapid in all her ways, and with the most 

 piercing black eyes I have ever seen in anybody's head. Men- 

 tally and physically (except in the matter of the beautiful eyes) 

 I am a piece of my mother, and except for my stature, which 

 used to be 5 feet 10, I should do very well for a " black Celt" ' 

 — supposed to be the worst variety of that type. My father 

 was fresh-coloured and grey-eyed, though dark- haired, good- 

 humoured, though of a quick temper, a kindly man, rather too 

 easy-going for this wicked world. There is a vein of him in 

 me, but the constituents have never mixed properly. ... I 

 know of Huxleys in Staffordshire, Worcestershire and Wales, 

 and I incline to think that the Huxleys of Huxley 

 [Cheshire] are responsible for most of us, and that, upon the 

 whole, we are mainly Iberian mongrels, with a good dash of 

 Norman and a little Saxon." This was written for my private 

 information, as bearing on certain inquiries into "genius" and 

 race, but there can be no objection to its publication now. 



Havelock Ellis. 



Quartz-Calcite Symmetrical Doublet. 



At the Bradford meeting of the British Association, Section 

 A, I offered to lend this lens for purposes of research to any 

 investigator who would satisfy me as to his qualification for 

 taking the necessary care of it. I am now ready to do so. 



Oaklands, Chard, November 26. J. W. Gifford. 



NO. 1623, VOL. 63] 



