XVII. Money and the Mechanism of Exchange. By W. Stanley Jevons, M.A., F.R.S. Eighth Edition. 5s.
XVIII. The Nature of Light. With a General Account of Physical Optics. By Dr. Eugene Lommel. With 188 Illustrations and a Table of Spectra in Chromo-lithography. Fourth Edition. 5s.
XIX. Animal Parasites and Messmates. By P. J. Van Beneden. With 83 Illustrations. Third Edition. 5s.
XX. Fermentation. By Professor Schützenberger. With 28 Illustrations. Fourth Edition. 5s.
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