Also, in 8vo., pp. 720, plates 24, price 21s., or coloured, 36s.,

A HISTORY OF INFUSORIAL ANIMALCULES, Living and Fossil, containing Descriptions of every species, British and Foreign, the methods of procuring and viewing them, &c., illustrated by numerous Engravings. By ANDREW PRITCHARD, M.R.I.

"There is no work extant in which so much valuable information concerning Infusoria (Animalcules) can be found, and every Microscopist should add it to his library."—Silliman's Journal.

London: WHITTAKER & CO., Ave Maria Lane.


XYLO-IODIDE OF SILVER, exclusively used at all the Photographic Establishments.—The superiority of this preparation is now universally acknowledged. Testimonials from the best Photographers and principal scientific men of the day, warrant the assertion, that hitherto no preparation has been discovered which produces uniformly such perfect pictures, combined with the greatest rapidity of action. In all cases where a quantity is required, the two solutions may be had at Wholesale price in separate Bottles, in which state it may be kept for years, and Exported to any Climate. Full instructions for use.

Caution.—Each Bottle is Stamped with a Red Label bearing my name, RICHARD W. THOMAS, Chemist, 10. Pall Mall, to counterfeit which is felony.

CYANOGEN SOAP: for removing all kinds of Photographic Stains. The Genuine is made only by the Inventor, and is secured with a Red Label bearing this Signature and Address, RICHARD W. THOMAS, CHEMIST. 10. PALL MALL, Manufacturer of Pure Photographic Chemicals: and may be procured of all respectable Chemists, in Pots at 1s., 2s., and 3s. 6d. each, through MESSRS. EDWARDS. 67. St. Paul's Churchyard; and MESSRS. BARCLAY & CO., 95. Farringdon Street, Wholesale Agents.