[9] OYSTER CULTURE IN MORBIHAN. 951 
granting to these several causes effects more or less important and de- 
cisive, we must seek others, and arrive at one of the most important 
subjects in oyster culture, the action of currents. We are convinced, 
and our opinion is founded upon the statements of the principal oyster- 
culturists of the department of Morbihan, such as MM. Chaumel, Gressy, 
and De Wolbock, that a current is indispensable to the life and welfare 
of the embryo. 
On the sea-coast, the tides vary in their movements according to the 
location. Near the shore, in the coves and mouths of rivers, the undula- 
tions, due to the tides, produce currents, which are called tidal currents. 
The rivers also have their currents, which on the flood tide carry the sea- 
waters towards the interior, and on the ebb come back laden with sedi- 
ment. 
There is something peculiar about these currents, which is that they 
are unequally distributed, and often, when there is an inward or flood 
current at the surface, the water is flowing outward below, and vice 
versa. It is now known that the parent oyster does not give out its 
spawn, excepting at the beginning of the flood tide. ‘‘ How admirable!” 
exclaims M. Chaumel. ‘ Never does the parent oyster, doubtless from 
the fear of having its young left upon dry land to perish, give them 
forth at the last of the ebb; all of the emissions which I have witnessed 
have taken place at the first of the flood, when the oysters begin to be 
well covered by the rising water, but never, never when the sea was 
about to leave them dry.” 
We can readily admit the instinct of the mother oyster, especially as 
we shall have later to speak of the instinct of the embryo; but we must 
also take into account the fact that the water is less pure and vivifying 
on the ebb than on the flood tide, and thus, in the former case, the 
conditions are much less favorable for the oysters. After remaining 
some length of time under the influence of the ebbing waters, they feel 
the contact of the incoming tide, under the revivifying action of which 
they throw out their spawn, for some distance around. 
Whether we take into consideration solely the action of the tides in 
connection with the spawning of oysters, or study their effects upon 
development in general, the result is always the same, as determined by 
careful observations, that the tides are necessary for the oyster and in- 
dispensable to its normal existence. If the oyster becomes fat and of a 
greenish color, it is an indication that it has been living under abnormal 
conditions, and it is well known that all animals confined in parks 
or basins, where they fatten, are not favorably situated for reproduc- 
ing. Thus, in locations where the current is wanting, the oyster, even 
though performing its natural functions, reproduces very imperfectly. 
But, however important the tidal current may be for the mother oyster, 
it is still more necessary to the embryo, which has not the power of 
transporting itself to any distance, by means of its temporary swimming 
organs. The area which it can traverse of its own free will, so to speak, 
