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extent by working upon it. The dredges or other implements 
used open the bed and spread it, thus giving more room for 
development, and allowing a greater amount of food to reach 
the animals. 
The mortality is great in all thickly populated tracts and 
in any closely united community, and it is evident that the 
removal of any of the brood oysters could not be effected 
without destroying the fecundity of the bed, did not this very 
removal influence the mortality among the young so as to al- 
low a larger number to come to maturity. But this removal 
, of brood oysters may become so great that the most violent 
exertions of nature to supply others are unequal to the de- 
mand. 
It must also be evident that as soon as the number of brood 
oysters is thus diminished, even to the slightest extent, the 
fecundity of the bed is impaired. 
This impairment constantly increases, influencing, as it does, 
both old and young. As the number of the latter decrease, 
so will the number of the former, and as that number is again 
and again diminished, the number of young produced by them 
must constantly diminish. Thus the cause for the destruction 
of the fecundity of the bed, and the gradual extinction of the 
animals upon it, can be readily understood and as easily com- 
prehended as the fact that the fecundity and preservation of 
the productive powers of a bed depends upon the number of 
mature, spawn-bearing oysters upon it. 
It is not meant by this that none but the mature oysters 
are capable of reproduction, as such is not the case, oysters of 
even six or nine months’ growth having been observed by me 
with ripe ova and spermatozoa in them, but the main depend- 
ence must be placed upon the adults in the community, as the 
spawn of the young growth is not considerable when com- 
pared with that of the other class. 
Without a knowledge of the number of oysters on a bed 
it is impossible to say what number should be removed, and 
as an attainment of the knowledge of the number on the bed 
is almost impossible, all that can be done is to keep the pro- 
portions between the young and the mature as nearly the 
