Zoological Collections. 327 



yellow tint when dissolved in minute portions in water ; and 

 this mixed with the blue of pure water would occasion sea-green. 

 I made many years ago, being on the Mer de Glace, an ex- 

 periment on this subject. I threw a small quantity of iodine, 

 a substance then recently discovered, into one of those deep 

 blue basins of water, which are so frequent on that glacier ; 

 and diffusing it as it dissolved with a stick, I saw the water 

 change first to sea-green in colour, then to grass-green, and 

 lastly, to yellowish-green. I do not, however, give this as a 

 proof, but only as a fact favourable to my conjecture. It 

 appears, however, to confirm the opinion, that snow and ice, 

 which are merely pure crystallized water, are always blue 

 when seen by transmitted light. I have often admired the 

 deep azure in crevices in masses of snow in severe winters, and 

 the same colour in the glaciers of Switzerland, particularly at 

 the arch where the Arve issues in the vallev of Chamouni. 



Art. XXIV.— ZOOLOGICAL COLLECTIONS. 



1. On the Natural History of the Par. 

 Our readers are doubtless aware that the par has been recently supposed, 

 by very competent judges, to be the young of the salmon. The reason for 

 this opinion we shall take an early opportunity of stating, and we shall be 

 obliged to any of our correspondents who can give us any information on 

 the subject. Sir Humphry Davy is of an opposite opinion, as appears from 

 the following extract from his Salmonia. 



" I think," says he, " the par, samlet, or brandling, common to most 

 of our rivers which communicate with the sea, has a claim to be consider- 

 ed a distinct species ; yet the history of this fish is so obscure, and so little 

 understood, that I perhaps ought not to venture to give an account of it. 

 I have seen this fish in the rivers of Wales and Herefordshire, and have 

 heard it asserted, on what appeared good authority, that it was a mule — 

 the offspring of a trout and a salmon. This opinion was supported by the 

 fact, that it is found only in streams which are occasionally visited by sal- 

 mon ; yet I think it more probable, if it is a mixed race, that it is produ- 

 ced by the sea trout and common trout. In a small river which runs into 

 the May near Ballina, in Ireland, I once caught in October a great num- 

 ber of small sea trout, which were generally of half a pound in weight, 

 and which were all males, and unless it be supposed that the females were 

 in the river likewise, and would not take the fly, these fish in which the 

 spermatic system was fully developed, could only have impregnated the 

 ova of the common river trout. The sea trout and river trout are indeed 

 so like each other in character, that such a mixture seems exceedingly pro- 



