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EECENT PAPERS IN THE ‘PHILOSOPHICAL TRANSACTIONS,’ 
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Series A.—Mathematical and Physical. 
A. 339. The Differential Invariants of a Surface, and their Geometric Significance. By A. E. Forsyte, 
M.A., Sc.D., F.E.S., Sadlerian Professor of Pure Mathematics in the University of Cambridge. 
Price 3s. 6(f. 
A. 340. On the Laws Governing Electric Discharges in Gases at Low Pressures. By W. K. Carr, B.A., 
Post-graduate Student, University of Toronto. Price 2s. 
A. 341. On the Dependence of the Eefractive Index of Gases on Temperature. By GeorgeW. Walker, 
M.A., A.E.C.Sc., Fellow of Trinity College, Cambridge. Price Is. 6d. ■ 
A. 342. Solar Eclipse of 1900, May 28.—General Discussion of Spectroscopic Eesults. By J. Evershed, 
F.E.A.S. Price 3s. 
A. 343. The Electrical Conductivity Imparted to a Vacuum by Hot Conductors. By 0. W. Eichardson, 
B.A., B.Sc., Fellow of Trinity College, Cambridge. Price 3s. 6fZ. 
A. 344. On the Formation of Definite Figures by the Deposition of Dust. By John Aitken, F.E.S. 
Price Is. 
A. 345. Title, Contents, Index, &c., Vol. 201. Price 6d. 
A. 346. Bakerian Lecture.—On the Constitution of the Copper-Tin Series of Alloys. By C. T. Heycock, 
F.E.S., and F. H. Neville, F.E.S. Price 7s. 6d. 
A. 347. The Combination of Hydrogen and Chlorine Under the Influence of Light. By P. V. Bevan, 
M.A., Fellow of Trinity College, Cambridge. Price 2.s. %d. 
Series B. — Biological. 
B. 210. The Structure and Development of the Stem in the Pteridophyta and Gymnosperms. By 
Edward C. Jeffrey, Ph.D. (Harvard). Price 3.s. 
B. 211. On the Structure of the Gills of the Lamellibranchia. By W. G. Eidewood, D.Sc., F.L.S., 
Lecturer on Biology at the Medical School of St. hlary’s Hospital, London. Price 9s. &d. 
B. 212. The Development of Echinus Esculentus, together with some Points in the Development of 
E. Miliaris and E. Acutus. By E. W. MacBride, M.A., D.Sc. (Lond.), sometime Fellow of 
St. John’s College, Cambridge; Strathcona Professor of Zoology in the McGill University, 
Montreal. Price 8s. 6d. 
B. 213. Title, Contents, Index, &c., Vol. 195. Price 6d. 
B. 214. The Seed-Fungus of Lolium Temulentum, L., the Darnel. By E. M. Freeman, M.S., University 
of Minnesota. Price 3s. 
B. 215. On the Histology of Uredo dispersa, Erikss., and the “Mycoplasm” Hypothesis. By 
H. Marshall Ward, Sc.D., F.E.S., Professor of Botany in the University of Cambridge. 
Price 3s. 
B. 216. The CEstrous Cycle and the Formation of the Corpus Luteum in the Sheep. By Francis H. A. 
Marshall, B.A. Price 4s. 
B. 217. On the Evolution of the Proboscidea. By C. W. Andrews, D.Sc., F.G.S., British Museiun 
(Natural History). Price Is. 
B. 218. Experiments in Hybridization, with Special Eeference to the Effect of Conditions on Dominance. 
By Leonard Doncaster, B.A., King’s College, Cambridge. Price 3s. 
B. 219. On Eeptilian Eemains from the Trias of Elgin. By G. A. Boulenger, F.E.S. Price 3s. Qd. 
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