Mr. A. W. E. O’Shaughnessy on Green Oysters. 225 
and which, when thus collected together in a lump, became 
visible to the naked eye. He says that, on placing a drop of 
the water under the microscope, he perceived thousands of 
Vibrios sporting about with every possible kind of motion— 
sometimes with a sudden jerk or impulsion forwards or back- 
wards, sometimes spinning round on their own axis like the 
needle of a compass, sometimes standing straight up on one 
end, or darting off with astonishing velocity at some other ani- 
malcule, and sticking one of their pointed extremities into him 
as if it were a Jance. 
That the green colour which makes its appearance in the 
oyster is really due to the absorption of these living atoms, M. 
Gaillon has expressed his firm conviction, both in the ‘ Journal 
de Physique’ above cited, and in the ‘ Memoirs of the Linnzan 
Society of Calvados.’ He assures us that as soon as the fresh 
water is again allowed to have free access to the reservoir the 
oysters gradually lose both the green hue and the altered flavour 
which accompanies it, although they are sometimes so thoroughly 
impregnated with the green matter that they do not quite lose 
it even in the winter, consequently long after the disappearance 
of the Vibrios; there is, however, a gradual and sensible dimi- 
nution in the tint. It is this duration of the green colour so 
long after the animalcules have ceased to exist, says M. Gaillon, 
which accounts for the assertion that green oysters may be ob- 
tained all the year round; those, he observes, who have never 
witnessed the intensity of the colour at certain seasons of the 
year would probably designate as green oysters any which showed 
the faintest remnant of that tint. 
According to all observers, it is the region of the branchiz or 
gills which exhibits this peculiarity the most strikingly. aNow 
M. Gaillon assures us, from having examined these organs with 
the microscope, and compared the orifices of the tubular fila- 
ments with the size of the animalcules, that the latter could not 
possibly enter the system of the oyster in that region. 
Perhaps one of the most significant facts recorded by M. 
Gaillon as the result of his laborious observations is, that at dif- 
ferent seasons of the year the water of the oyster-“ parks” pre- 
sents very different tints, being sometimes brown, at others 
green or yellow—both the brown and the yellow being equally 
the result of the abundant presence of microscopical animalcules 
of a different species from the green Vibrio ostrearius. The 
brown species, we are told, has as striking an effect on the colour 
of the oyster as the green one, and greatly improves its flavour ; 
whereas the yellow are considered prejudicial. 
With reference to these so-called animalcules, we need scarcely 
state that the atoms hitherto referred to the genus Vibrio are 
Ann. & Mag. N. Hist. Ser.3. Vol. xvii. 16 
