464 
ture of the zygopterid sector (Ms) was found to be 
normal. 
occurs in one wing, trachea M, becoming hitched on 
to Ms near its base, while the supervening imaginal 
venation remains normal, so that the base of M, 
appears on the larval wing as a true bridge. This 
suggests that bridges in general are not czenogenetic 
developments in the venation, as held by Needham, 
but that they are the archaic condition, from which 
the tracheation has departed by specialisation. The 
question of the homology between Rs in Anisoptera 
and Ms in Zygoptera is dealt with by a complete mar- 
shalling of all the known evidence, both structural and 
ontogenetic. This is shown to be absolutely against 
the supposed homology. As a more probable explana- 
tion, the author suggests that the presence of two 
oblique veins in the archaic Petalurinee and Cordulega- 
strinz indicates the presence of both Ms and Rs in 
these forms, but that the Zvgoptera, as a whole, have 
fost Rs by suppression at the subnodus, while all the 
rest of the Anisoptera only retain Ms as the bridge- 
vein basally, the more distal portion having become 
fused with Rs. 
BOOKS RECEIVED. 
How We Learn. By W. H. S. Jones. Pp. vii+64. 
(Cambridge: At the University Press.) 1s. 6d. 
Nature Study Lessons seasonably Arranged. By 
J. B. Philip. Pp. ix+147. (Cambridge: At the Uni- 
versity Press.) 25, 6d. net. 
Elementary Physics for Engineers. By J. Paley 
Yorke. Pp. viiit165. (Cambridge: At the Uni- 
versity Press.) 4s. net. 
- Annuaire pour l’an i917 publié par le Bureau des 
Longitudes. Avec des Notices Scientifiques. (Paris : 
Gauthier-Villars et Cie.) 2 francs net. 
The My‘hology of. All Races. Oceanic. By Prof. 
R. B. Dixon. Pp. xv+364+plates xxiii and map. 
(Boston, Mass. : Marshall Jones Co.) 
The Problem of Pain in Nature. 
Pp. 131+7 illustrations. 
d, net. 
Science in the School. 
Pp. 20. (Cambridge: W. 
éd. net. 
By C. F. Newall. 
(Paisley: A. Gardner.) 
By Sir Clifford Allbutt. 
Heffer. and Sons, Ltd.) 
DIARY OF SOCIETIES. 
THURSDAY, Fesrvary 8. 
Rovat Society, at 4.30.—The Dynamics of Revolving Fluids: Lord 
Rayleigh.—Deflection of the Vertical by Tidal Loading of the Earth's 
Surface: Prof. H, Lamb.—Spontaneous Generation of Heat in Recently 
Hardened Steel: C. F. Brush and Sir R. Hadfield, 
Rovat Institution, at 3.—The Mechanism of Chemical Change: Prof. 
F. G. Donnan. - 
INSTITUTION OF ELECTRICAL ENGINEERS, at 8.—Frequency Changers: 
R. Townend. 
Optica. Society, at 7.30,—Annual-Meeting:—More Notes on Glass Grind- 
ing and Polishing: J. W. French. 
FRIDAY, Frprvary 9. 
Rovat Instirvrion; at 5.30.—Experimental Phonetics and its Utility to 
the Linguist: D. Jones. 
Rovat Asrronomicat Society, at 5.—Anniversary Meeting. 
MALACOLOGICAL SOCIETY, at 7-—Annual Meeting. Presidential Address: 
Systematic List of the Marginellide: J. R. le B. Tomlin. 
PHysicat SOCIETY, at 5.—A Special Test on the Gravitation Temperature 
Effect : Dr. P. E. Shaw and C. Hayes.—T'o Measure Pressure in a High 
Vacuum by Observation of Logarithmic Decrement: Dr. P. E. Shaw.— 
Note on the Calculation of the Coefficient of Diffusion of a Salt at a Definite 
Concentration: Dr. A. Griffiths. 
NO. 2467, VoL. 98] 
But occasionally a peculiar abnormality | 
NATURE 
[FEBRUARY 8, 1917 be’ 
.* — 
SATURDAY, Yesruary 10, Og zt i 
Ceramic Society, at 7.—Acid and Basic Furnace Lining. pe 
1 
MONDAY, Fesrvary 12 te = 
Royat Society or Arrs, at 4.30.—Town Planning and Civic Athi Be 
Prof. A. Beresford Pite. + . ve a iN 
TUESDAY, Fesrvary 13. 
Roya. IwvstiruTION, at 3.—Pain and its Nervous 
Sherrington. 
WEDNESDAY, FEBRvUARY 14. % +o 
Ree Satins oF Arts, at 4.30.—Highways and Footpaths: Lawrence 4 
ubb. ae) ae 
THURSDAY, Frprvary 15. : oS 
Roya. (Society, at 4.30.—Prvbable Papers: Structure and ‘Perdiopane é 
of the Tubular Enamel of tue Sparide and Labride: Dr. J. H. me > 4 
mery.—(1) Distribution in Wheat, Rice and Maize Grainsofthe Substance __ 
the Deficiency of which ina Diet causes Polyneuritis in Birds and Beri- 
beri in Man. (2) Effect of Exposure to Tewwperature at or above roo"C 
upon the Substance (Vitamine) whose Deficiency in a Diet causes Poly- 
a in Birds and Beri-beri in Man: Harriette Chick and E. M. 
ume. ‘ 
Royat Institution, at 3.—The Mechanism of Chemical Change: Prof. 
F. G. Donnan. . Ba 
Society or Grass TrcuNnoLoGcy, at the University, Western Bank 
Sheffield, at 4.30.—The Annealing of Glass: F. Twyman. a 
RoyaL SOCIETY OF ARTS, at 4.30. 3 
IxsTiTuTION oF MINING AND METALLURGY, at 5.30.—The Wet Asay, 
of Tin Concentrate: H. W. Hutchin.—Hydrautic ‘fin Mining in Swazi- 
land: J. Jervis Garrard. i q 
FRIDAY, Frervuary 16. 5 
Royvat InstiTuTION, at _5.30.—Authors’ Dedications in the Seventeenth 7 
Century: The Dean of Durham. ‘ ve; 
INSTITUTION OF MECHANICAL ENGINEERS, at 6.—Annual General f 
Meeting. : § 
Gero.ocicat Society, at 3.—Annual General Meeting. sae 
SATURDAY, Fesruary “8 4 é 
Rovat Institution, at 3.—The Mystery of Counterpoint: Dr. H. : 
Walford Davies. | 
CONTENTS. PAGE 
Sea-trout.. By C. T.°R.. . 5. <n!) a> oe 
Photographic Recording. ByC.J......... 
Gur Bookshelf. 33. 3.< 10-7 sak Se 
Letters to the Editor:— ; 
The Aurora, Magnetic Storm, and Sun-spot of Jan- 
uary 4.—Rev. A. .L, Cortie, S.J... . . 5 73 446 ; 
Forns of Weathering in Magnesian Limestone. (///us- 
trated.) George Abbott ..... os) oe 
Teitiary Igneous Rocks of the Pyrenees.—P. W. me 
Stuart-Menteath ree 
The American Association for the Advancement 
OF Selernice i. iy. 1s ah rd de hee . 
Research ‘in Timber. =.) ose hasta 
OCS) «se fee le: eer fells. ale) se) een 
Our Astronomical Column :— ” 
The Lake Okechobee Meteorite. . ..... 
Cluster Variables. 1:c mua uae 
United States Naval Observatory ..% . ..«.- 
International and Natural Law . eerie 
Forthcoming Books of Science..... . 
Research in Industrial Laboratories ...... 
University and Educational Intelligence .... . 
Societies and Academies. ....*. ..--s 
Books Received ......... 
Diary of Societies"... - 2-50) .°o . aisha 
e 2 1@ 6 a oe 
Editorial and Publishing Offices : 
MACMILLAN & CO., Lrp., 
MARTIN’S STREET, LONDON, 
Si W.c. 
Advertisements and business letters to be addressed to the 
Publishers. 
ni 
< « ne Mi 
Editorial Communications to the Editor. 
Telegraphic Address: Puusis, Lonpon. 
Telephone Number: GERRARD 8830. 
