[47] OYSTER CULTURE. Ns, 
ground is obtained, which is visited by pure and aerated water, where 
oysters can be planted and where they can flourish unmolested; often 
upon such places a self-planting takes place, that is, the young, floating 
in the water after having escaped from some natural bed, finding the 
place in excellent condition for their reception, attach themselves to the 
rocks and form a new colony. When the deposit of mud is once com- 
pletely broken up, the rocks, by the aid of which this result has been 
accomplished, will serve to prevent its return, and as all the rocks will 
not be required for this purpose some of them can be used as fixed pave- 
ment collectors, the advantages and disadvantages of which have been 
noticed upon a previous page. Certain of the walls may be entirely re- 
moved and shells and valves of diverse mollusks, found in abundance 
nearly everywhere, can be scattered about in the intermediate zones, or 
other collectors, either fixed or movable, may be employed in the spaces 
between the lines of breakers. 
Sandy bottoms.—Sandy bottoms, if the sand forms a comparatively 
thin layer resting upon a sure and solid subsoil, so that the action of 
the currents, tides, and heavy seas is never intense enough to produce 
great changes, capable of covering up the oysters which may be placed 
upon them, are the best and may be worked without any fear. All 
that is necessary, when the oysters are planted, is to distribute a layer 
of shells over the bottom, and these shelis sinking slightly in the sand 
will give it a certain degree of fixity, and, gradually consolidating by the 
attachment of oysters to them, will soon transform the entire bottom 
and even change it into a bed of great value. 
Bottoms of grass or weeds.—Certain bottoms become invaded by an 
abundant submarine vegetation consisting of grass, various kinds of sea- 
wrack or alge, including the maérle. In their natural condition these 
regions cannot be utilized for the cultivation of the oyster. By their 
presence these plants serve to entirely stifle both old and young oysters, 
and they moreover give refuge to multitudes of crustaceans, mollusks, 
and polyps, which gain their nutriment principally by feeding upon the 
young of other marine animals, or in the case of some mollusks, furnished 
with a boring tongue, they pierce the shell of the oyster and gradually 
eat out the soft animal parts contained within it. It is necessary, then, 
if one wishes to cultivate these bottoms and raise oysters there, to com- 
mence by dragging up all the parasitic vegetation upon them, and then, 
to prevent their reappearance, the entire bottom must be covered with 
a thick layer of shells and broken fragments of rocks, which must be 
pounded down nearly, if not quite, to the subsoil. But even then it will 
be well to keep a constant lookout over these bottoms, for marine veg- 
etation has a strong tendency to reproduce itself in the same places, 
and holds its ground for a long time by means either of subterranean 
roots or of seeds. It is only by perseverance that ‘they can be finally 
eradicated. Only after this has been accomplished can oysters be planted 
without danger of losing both the young and future harvests. What 
