666 
NATURE 
[AUGUST 12, 1915 

ently, is there any trace of a larval skeleton. The 
whole animal is ciliated, but the cilia are not collected 
into bands. The young sea-urchin develops on one 
side of the embryo, near the mouth. The aboral part 
serves as a food-reservoir, and becomes finally quite 
overgrown and enclosed within the urchin’s body. 
The young animal may sink to the bottom or remain 
swimming at the surface. 
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Revision Papers in Algebra. By W. G. Borchardt. 
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Post-Mortem Methods. . By Prof. J. M. Beattie. 
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The Study of Plants. By Dr. T. W. Woodhead. 
Pp. 440. (Oxford: At the Clarendon Press.) 5s. 6d. 
Publications of West Hendon House Observatory, 
Sunderland. No. iv., Meteorological Observations 
chiefly at Sunderland. By T. W. Backhouse. Pp. 
v+188. (Sunderland: Hills and Co.) 
The Sacred Chank of India. By J. Hornell. Pp. 
viiit+181+18 plates. (Madras: Government Press.) 
Experimental Harmonic Motion. By Dr. G. F. C. 
Searle. Pp. x+92. (Cambridge: At the University 
Press.) 4s. 6d. net. 
Annals of the Cape Observatory. Vol. xii., part 1: 
Determination of the Mass of Jupiter and Elements 
of the Orbits of its Satellites, from Observations made 
with the Cape Heliometer. By Sir D. Gill and W. H. 
Finlay; reduced and discussed by Prof. W. de Sitter. 
Pp. 173. (Edinburgh: H.M.S.O.; London: Wyman 
and Sons, Ltd.) 6s. 
Cape Astrographic Zones. Vol. ii.: Catalogue of 
Rectangular Co-ordinates and Diameters of Star 
Images, derived from Photographs taken at the Royal 
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Zone—42°. Pp. xxxviiit+4o9. (Edinburgh: H.M.S.O.; 
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Results of Meridian Observations of Stars made at 
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Papers from the Department of Marine Biology of 
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NO. 2389, VOL. 95] 

Mineral Resources of Minas Geraes (Brazil). By 
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The World’s Supply of Potash. Pp. 47. (London: 
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Prof. Edward Forbes’ Centenary, 1915. Pp. 45. 
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Health in the Camp. By Prof. H. R. Kenwood. 

Pp. 58, (London: H. K. Lewis and Co., Ltd.) 3d. 
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CONTENTS. PAGE 
The Problems of Science. ByG.B.M, ..... 639 
Physical Chemistry of Molecules. By H. M.D... 640 
The Fundamentals of Three-Colour Photography. 
13} Ce ee REE ca) Sms ava ota n 641 
Medicines and their Manipulation ........ 641 
MindjinvAnimals.. By. Joyers sie cme nee 642 
OurgBookshelf ... ..... .....53- Sees ee a 642 
Letters to the Editor:— 
The Principle of Similitude.—J. L. ; Lord Rayleigh, 
(OR 09 ACHES rig of oe dinim en A 644 
The Probable Error of the Amplitudes in a Fourier 
Series obtained from a Given Set of Observations. — 
WV.) Dines 3B aR S oles aan ne 644 
On the Character of the “S” Sound. By Lord 
Rayleizbs(O5M.> ER. Saco ero -fe iene 645 
Gauges eg, S20 5 oc fey, coll ear siarom eee ane ra ‘ 646 
FaunayAntaretica. (7//ustrafed:) s.) 2 ve nee 648 
INGtesittstiet 2h.5h 0.0.) a rh ere et re ee 649 
Our Astronomical Column :— 
Absolute Scales of Photographic and Photovisual 
IMepmitudes;.' .\ 1.5) eccl sele mepene esac aaa meee 654 
Meteorology'of the!Sun# iio. acne emia neene 655 
Vartable:Stars:.: :). ... 4) oanatesuael actateileststge anne nea 655 
Short; ReriedWariable:Starsy ayn) geist teens 655 
The Manchester Meeting of the British Association 655 
The Study of Heredity. By G.H.C........ 657 
Biometrics and ‘Man... 25) ee ae eee 658 
Reports on Mining Industries ©... 2... 5: 658 
Trypanosomes Causing Disease in Man and Do- 
mestic Animals in Central Africa. (J///ustrated.) 
By Sin David) Bruce, CoBi i. Ress nn i esis 659 
University and Educational Intelligence ..... 664 
Societiestand! Academies i971 aaiae eee oie 665 
BooksiRieceivied’ >) 5.)?.)\-/: arse meanest enn 666 


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