[15] OYSTER AND MUSSEL INDUSTRIES. 839 
suitable size; it takes three or even four years to give them the degree 
of perfection which characterizes the best products of Marennes. But 
the greater number of those which are raised in claires are, unfortu- 
nately for the trade and for consumption, far from having these good 
qualities. Placed when adult in the reservoirs, they become green in a 
a few days, and speculators, abusing a property which adds to the 
mercantile value of their products, carry them to market without having 
taken the trouble to give them the benefit of prolonged cultivation. 
Thus they avoid all the expenses of manipulation, and can prepare several 
crops each year upon the same bed. It is this that enriches oyster- 
culturists. 
The oysters of Marennes donot become green in summer, either because 
during this season the claires lose the property of transmitting this color, 
or because the oysters, having become milky, are then opposed to this 
influence. Those which had previously experienced the effects blanch 
by degrees as the time of reproduction approaches, and, when the spawn- 
ing season has come, lose their color entirely; on the other hand, white 
oysters deposited at this period of the year remain white. ‘They do not 
recover from this temporary loss until some time in the month of August, 
and itis notatall inconvenient for the trade, as the coloration reappears 
immediately after spawning. This coloring is not general; it shows 
itself particularly upon the respiratory organs, that is to say, upon the 
four branchial lamine. The internal surface of the first pair of labial 
palpi, the external surface of the second pair, and that portion of the 
intestinal canal which surrounds the exterior of the great attaching 
muscle also show visible traces of it. No other organ is affected by it. 
The liver, it is true, presents a more or less intense greenish tint; but 
this tint is by no means equal to that of the gills and the labial palpi. 
The green matter which thus invades the parenchyma of the organs 
which it prefers, invades the contents of the cells which form the tissues 
of these organs about the same as the substance which colors the yelk 
of a bird’s egg, or the corpus luteum of the ovary of amammal. Chemical 
analysis leads us to believe that this matter must be distinct from all 
ereen substances, animal or vegetable, studied up to the present day, 
for reagents do not affect it in the same manner.* 
*T give here the result of experiments which M. Berthelot has had the kindness to 
make, at my request, with a view to determine the nature of the matter which colors 
the branchi of the oysters of Marennes. 
These organs have been treated successively : 
First. By water, which has become slimy without being colored or diminishing the 
color of the gills. 
Second. By ether, which likewise had no action upon the coloring matter. 
Third. By crystallizable acetic acid, which precipitated traces of a yellowish sub- 
stance which was neutralized by the yellow prussiate of potash, though it increased 
considerably the coloring of the gills. 
‘Fourth. By cold potash, which diminished the coloring precipitated by the acetic 
acid, but without causing it to disappear. 
By this series of manipulations the branchiz lose their coloration in part, and are 
