OYSTERS, 25% 
oysters breed there, depends. If carefully attended 
to, a bed may last any length of time; but if 
neglected, it will become overgrown with weed 
and buried in mud, so that it can only be reclaimed 
by restocking at a great expense, or 1s altogether 
destroyed. Artificial beds, for the purpose of 
keeping a supply at hand for the London market, 
are said to have been commenced about the year 
1700, by the Kent and Kssex Companies of 
Dredgers. The oyster does not breed freely, often 
not at all, on artificial beds, so that they require to 
be constantly restocked; and when they do spawn 
under such circumstances, the fry are said seldom 
to come to perfection. On their natural grounds 
they spawn profusely during the season, ¢.e. during 
the summer months.” 
The nature of the “ spat”’ is thus explained by 
Sir Anthony Carlisle: ‘‘ Oysters are viviparous, and 
the young are found within the tracheal passages, 
and between the folds of the coverlit (mantle), 
during the months of June and July in this 
climate. In its first state the oyster exhibits two 
semi-orbicular films, of transparent shell, which 
are continually opening and closing at regular 
intervals. The whole brood are associated together 
by being involved in a viscid slime, and in that 
state called the spat; it being common among vivi- 
parous animals of this kind to have their spawn 
deposited in contact with the lungs; the involving 
slime serves as the first nutriment, and we may 
infer, that the foetal food so influenced by the gills 
is, at the same time, a respiratory supply to the 
imperfectly formed young.” * 
** In London the chief consumption of common . 
* Hunterian Oration, 1826. 
