Nature, J 
August iz, 1923 
X-Ray: Accessories, New, Watson and Sons (Electro- 
Medical), Ltd., 440; Crystal Analysis, Relation be- 
tween Molecular and Crystal Symmetry as shown by, 
G. Shearer, 34 ‘ 
X-Rays: in Calcite, The Refraction of, B. Davis and H. M. 
Terrill, 207; in Liquids, The Scattering of, Prof. 
C. V. Raman, 185; of Great Wave-length, The 
Optical Properties of, M. Holweck, 451 ; The Diffrac- 
tion of the, by Smectic Bodies, M. de Broglie and E. 
Friedel, 487 ; The Effect of, of different Wave-lengths 
upon some Animal Tissues, Prof. S. Russ, 793; The 
Industrial Applications of, P. H. S. Kempton, 665 ; 
The Release of Electrons by, Prof. S. Russ, 534 
Yale University Observatory, A New Photographic Tele- 
scope for the, 681 
Yearbook of the Learned World, A, 425 
Yeast Extracts, Use of, in Diabetes, L. B. Winter and 
W. Smith, 327 
Title Index Ixi 
Yorkshire : Botanical Survey and Ecology in, Dr. T. W. 
Woodhead, 511 ; The West Riding of, B. Hobson, 180 
Young’s Modulus and the Ratio of Density to Atomic 
Mass, The Relation between, T. Peczalski, 383 
Zebra, Two New Species of Nematodes from the, Gertrud 
Theiler, 623 
Zeipel’s Condensation-theorem and Related Results, Sir 
Thomas Muir, 624 
Zimbabwe, Archeological Exploration at, H. R. Douslin, 442 
Zinc, Isotopes of, Separation of, A. C. Egerton and W. B. 
Lee, 381 . 
Zodiacal Light, The, W. F. Denning, 338 
Zoological: Gardens, retirement of R. I. Pocock; ap- 
pointment of Dr. G. M. Vevers as Superintendent, 
126; Nomenclature, Musca and Calliphora, Prof. 
C. W. Stiles, 115; Record, The, 578, 584, 625; 
Results of a Tour in the Far East (Fish, Part 1.), S. L. 
Hora, 555; Society of London, Yearly Report of the, 611 
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