Royal Institution of Great Britain. 299 



Irunuifrous, which name, as it had appeared on the plate, he wished 

 to be retained to the species. The H^hite-crowned Crow of General 

 Hardwicke, which had been figured in the ' Century,' was erroneously- 

 called a Garrulus. It seems rather to belong to the tribe of Denti- 

 rostres, and the genus Cindosoma. Some verbal errors in the lettering 

 were also pointed outj all of which, together with the mistakes in 

 the names, Mr. Vigors attributed to the hurry in which some of the 

 numbers of the work were obliged to be printed off in order to answer 

 the demand that was made for them on the day of the monthly pub- 

 lication. And he concluded by trusting that the supporters of the 

 work, and the lovers of science would overlook these accidental ble- 

 mishes in the lettering of the plates in the midst of so many superior 

 excellencies. 



FRIDAY-EVENING PROCEEDINGS AT THE ROYAL INSTITUTION 

 OF GREAT BRITAIN. 



Jan. 20. — These meetings commenced on this evening. Mr. 

 Brande described in the lecture-room the process followed at the 

 Royal Mint, under the direction of Mr. Mathison, and also abroad, 

 by which small quantities of gold are extracted from silver, and 

 especially from our silver coinage; and also small quantities of 

 silver from gold. It consists in boiling the alloy of silver and gold 

 in sulphuric acid, by which the silver is taken out and the gold left ; 

 then the silver is precipitated, and made to resume the marketable 

 state. The influence over commerce, due to the circumstance of 

 these alloys occurring naturally, and to the oeconomical means of 

 separating them afiorded by the process described, were explained, 

 and every part of the process was illustrated by experiments. 



Numerous geological, philosophical, and literary presents were 

 laid upon the tables at this the first meeting of the season. 



Jan. 27. — Mr. Faraday gave an account of Dr. J. R. Johnson's re- 

 cent researches on the reproductive power of Planaricc. These 

 animals are allied to leeches, live in water, have a head, and usually 

 eyes : they feed by a kind of proboscis, which they put forth from 

 the middle of the under part of the body. Several species deposit 

 eggs ; others increase by subdivisions of themselves, the parts se- 

 parated becoming perfect animals. They are from a quarter of an 

 inch to an inch in length, and may be found in the ponds near the 

 shooting-house at Battersea, and elsewhere, adhering to those parts of 

 the leaves of the aquatic plants which grow beneath the water. 



When one of these animals is cut in halves, the anterior half gets a 

 new termination, and the posterior half a new head. When cut into 

 four, five, six, or even ten pieces, all have lived and become complete. 

 When partly divided, as down the head, each half fre(]uently becomes 

 a complete head with the full complement of eyes ; or if the division 

 closes, a head with four, five, six eyes, or more, results : in fact the 

 animals multiply under the knife. 



Many animals were upon the table in different states, as double- 

 headed, double-bodied, many-eyed, fvc. 



Feb. 3. — Mr. Griffiths gave an account of his views of the mcan- 

 2 Q 2 ings 



