196 Mr. Howard Martin on Oysters. 
It has been said that spat have no choice as to their place of 
attachment, but Iam very doubtful as to this. I have known 
cases where spat in enclosed ponds containing tiles, hurdles, and 
faggots as ‘collectors,’ has shown a decided preference for the 
tiles, and for the under side of the tiles when they were so placed 
on the bottom of the ponds as to form low pointed arches eight 
or nine inches in height. (A diagram was shown illustrating 
further development of spat and attachment to ‘collectors.”’) 
The shell of the spat and of the mature oyster grows by 
throwing out glassy calcareous rings on the edges of the shell 
farthest from the hinge, and by these rings it is said the age of 
the oyster can be ascertained. The ages of some oysters as 
shown by these rings would be twelve or fifteen years; the 
marketable age is three to seven. (Diagram showing position in 
shell of mature oyster, which is occupied by the valves or shells 
of the black spat.) The valves of the black spat form the hinge 
of the mature oyster-shells. 
Young oysters in enclosed ponds or similar fisheries, under 
close cultivation, are detached from the ‘collectors’? when about 
nine months old, and placed in the “laying ground,” where they 
obtain more food. Here they need protection—(1) because they 
are very light and liable to be carried away by tides, and (2) 
because their shells are very weak, and therefore easily opened 
by crabs, who are fond of eating them. In some fisheries they 
are placed in small ponds prepared for the purpose between high 
and low water mark; in others, especially in France, they are 
placed in ambulances (trays fitted into large boxes with gratings), 
and moored to suitable places. When spat is thickly attached 
to the ‘‘collectors,” and is not artificially removed, the young 
oysters as they grow shoulder each other into a vertical position, 
until they break the attachment and free each other ; but this 
hinders their growth and spoils their shape, and therefore their 
future value. 
It is then important that the ‘‘collectors” should be of such 
materials as will allow of the young oyster being removed with- 
out injury. In open fisheries in England empty oyster-shells, 
called ‘“‘cultch,” is the kind of “collector”? most im use, and 
probably the best in those situations. In enclosed ponds hurdles 
and faggots are very useful “collectors,” because the bark is 
easily peeled off with the young oysters attached ; but probably 
the best ‘‘collectors” are flat tiles with a coating of clay and 
cement. Wire-netting has sometimes been used. ~ 
Young oysters over a year are called ‘‘brood,” and are saleable 
to be laid down in fisheries, in which oysters grow well but do 
not breed. It is doubtful if adult oysters will re-attach them- 
selves after they have been once removed, but it is true that an 
oyster laid on its flat shell will turn itself over. 
ee 
