176 ML A. Valenciennes on the Causes of the 
Albumen prepared by dissolving serum which had been dried in the open air 
at the usual temperature, then precipitating it in cold alcohol, and purify- 
ing it with boiled ether. 
1st Analysis. 2d Analysis. 
Carbon, 654.726 54.765 
Hydrogen, 7.312 7.065 : i 
Nitrogen, 18.105 18.118 ~ Catb.: to Nitr.: 2: 7:1. 
Oxygen, 19.857 20.052 
Serum of the Blood, subjected, without previous solution, to the action of cold 
alcohol and boiling ether. 
Carbon, . . . . 65.233 
Hydrogen, . . . 7.156 eee Seas 
Nitrogen, | cpate ame Loe ao st Carb. : Nitr. 2:7: 1. 
Oxygen, .. . . 19.836 
All these analyses were made in the laboratory of Giessen, by Dr 
Scherer; and I have taken all necessary pains to ensure their accuracy. 
On the Causes of the Green Colour in certain kinds of Oysters. 
By M. A. VaLencrennes. 
Tue observations I have made on green oysters have led to 
some results which appear to me sufficiently curious to deserve 
being communicated to the Academy. 
It is well known that the explanations hitherto given of the 
colouring of oysters still leaves much to be desired. 
Some have thought that feeding on certain ulvz was the 
cause of the green colour in oysters ; others have ascribed it 
to the absorption of the microscopic animalcules named Vibrio 
ostrearius ; while others have maintained that oysters change 
colour, and become green, solely by absorbing the green mat- 
ter produced in the enclosures where they are kept. 
It may be remarked, in the outset, that we are occupied, as 
too often happens, in explaining a singular phenomenon, with- 
out observing how it takes place in an animal which we may 
examine by hundreds every day. 
In a green oyster there is only a single organ visible on the 
exterior which assumes this colour; this is the four leaflets of 
the branchiz. By raising the upper part of the mouth, we 
perceive that only the inner surface of the labial palpi is green, 
and on examining the internal parts, we speedily ascertain 
that the intestinal canal alone beyond the stomach is of a fine 
