840 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [16], 
Authors do not agree upon the origin of this coloring principle. Some 
suppose that it is the soil itself which contains it; others that it is an 
animalcule ( Vibrio ostrearius), or certain alge which produces it’; others, 
finally, attribute it to a sort of jaundice or to a diseased state of the 
liver, whose superabundant secretions tinge with green the parenchyma 
of the respiratory apparatus of the animals influenced by the treatment 
to which they are subjected in the claires. , 
Of these three opinions, the one which attributes the power of pro- 
ducing a green color to the nature of the spoil would seem most nearly 
correct. Both the comparative analysis of the soil taken from the claires 
which produce the green color and from those which do not, and the 
experiments of the commission of pisciculture of La Rochelle,j have at 
least a tendency to establish this. These experiments prove that the 
bluish-green marls have, like the soil of Marennes, and to the same 
degree, the property of coloring oysters; so that, according to the re- 
sults which this commission has obtained in the artificial basins where 
they have pursued their experiments, it would be safe to conclude that 
whenever we can organize clay reservoirs upon our coast, similar to 
those of which I speak, we will succeed in creating the same industry 
as upon the shores of the Bay of Seudre. 
This industry, extended to districts in which it has not yet been 
disintegrated into viscous flakes, in the midst of which the coloring matter is con- 
centrated. 
Fifth. The green substance treated by sulphurous acid in solution is not Ceprived 
of color; on the contrary, it is deepened in color as by the acetic acid. 
Sixth. Treated by chlorine water the color entirely disappears. 
Seventh. Heated to ared heat and incinerated, then treated by a drop of diluted 
muriatic acid, it gave a blue precipitate with prussiate of potash, which indicates the 
presence of an appreciable proportion of iron in the incinerated tissues. 
We may justly regard this iron as one of the essential elements of the coloring mat- 
ter, although this substance has not been isolated. 
In conclusion, the coloring matter of the oysters of Marennes does not resemble either 
that of the blood, or the bile, nor is it like most of the vegetable or animal coloring 
matters. The coloring matter of the blood contains iron, it is true; but the properties 
of this matter as well as the color are very different. 
The earth of the claires, which do not make the oysters green, and that of the basins, 
which do transmit to them this quality, differ notably in the proportions of the ele- 
ments which enter into their composition. According to the analyses which M. Ber- 
thelot has kindly made for me, independently of the ordinary elements of the soil, 
both are equally colored by the sulphuret of iron, contained in animal and vegetable 
matter in decomposition, and are impregnated with water containing salt and a little 
chloride of magnesium; but in the first these elements are much less decided than in 
the second; the sulphuret of iron is less abundant, and presents less decided tints; the 
vegetable and animal matters predominate less; the chloride of sodium is found in 
smaller quantity, and of the salts of magnesia there are only traces. Though these 
differences, seem of such little importance, may they not be the cause of the differences 
presented by the products raised in these claires? This is a point which subsequent 
experiments, made in these places, will doubtless soon clear up. 
t Rapport fait a la Société des sciences naturelles de la Charente-In ferieuires par la Com- 
mission de pisciculture, etc.’ La Rochelle, 1853. 
