of the Fishery Board for Scotland. 
223 
the coast about the mouth of the Gironde, but it is not cultivated in the 
waters of the Morbihan. It is a dioecious form, while the common oyster 
is monoecious or hermaphrodite. 
For convenience, the system of oyster cultivation may be treated under 
two divisions : 1. The Production of Oysters, 2. The Growth of Oysters. 
The Production of Oysters. 
The object of oyster-culture at this stage is to obtain the greatest possible 
quantity of spat in such a position that the young oysters can be readily 
transferred for purposes of growth from one locality to another. 
Pisciculture has reached a high state of development, so far as artificial 
fertilisation is concerned. Artificial fecundation has made the stocking of 
depleted lakes and streams possible in this country, in America, and in 
other countries, but the biological conditions which it is necessary to 
observe prevent the same method being followed in the case of the 
oyster. In those molluscs where the young undergo development within 
the mantle chamber or the gills of the mother, no artificial medium has 
been found which can take the place of the fluid found within the maternal 
shell. Till this is done it will be idle to look for results in the fertilisation 
of the oyster after the same method as is adopted among teleosteans. 
The eggs of Ostrea edulis are fertilised within the body of the animal, 
and the first stages in the life history of the young oyster are passed 
within the valves of the mother. After the young oyster attains a 
certain stage in its development it leaves its mother, and is carried 
along by the currents of water in the sea. It then gives up its pelagic 
existence and becomes moored to some solid substance in the water, 
where it remains fixed for the rest of its life, unless it is artificially 
removed. By nature the young oyster becomes attached by the apex or 
umbo of the concave valve to shells, stones, and other solids on the bottom 
of the neighbouring areas. Sometimes, especially where there are strong 
currents, the pelagic oyster may be carried long distances, but where the 
dispersive forces are not great it settles down in the neighbourhood to a 
fixed existence. It is at this stage that man can greatly assist by supply- 
ing fit resting places — collectors — for the spat. 
For the collection of spat the first essential condition is the presence 
of a large number of mother-oysters. M. Coste's classical experiment 
kept this in view, and the French Government have continued his policy. 
Of the millions of millions of the free swimming spat only a small pro- 
portion becomes fixed and captured by man. The policy therefore of the 
French Government, in setting aside certain banks — bancs reserves — and 
of the parquers in keeping a large supply of mother-oysters in suitable 
localities for spatting purposes, assures, if the conditions are favourable, 
an abundant quantity of young oysters. The Dutch lessees also keep 
large stocks of oysters, and their collectors receive a supply of spat from 
the embryos set free from the breeding-oysters. Both French and Dutch 
ostreiculturists, who possess an experience of other than their own coasts, 
urge the necessity, if oysters are to be laid down in suitable local ties in 
Scotland, that they should be laid down in quantity, and suggest millions 
instead of thousands, if oyster-culture is to be a success. One ostrei- 
culturist whom I met near St. Malo, informed me that his firm had 
sold to M. Coste two and a half millions of oysters, which were planted 
in one bay, where there were previously natural banks. 
Different forms of collectors have been employed at different times. In 
the infancy of oyster-culture bundles of twigs, anchored above the bottom, 
were the favourite collectors, but as the French perfected themselves in 
