774. REPORT OF COMMISSIONER OF FISH AND FISHERIES. [22] 
work their way, by means of their walking appendages, back to the shore 
where they were born. From this time onward their form is like that of 
the adult, or nearly so, but they are very small and grow very slowly. 
They increase in size only at intervals, that is, at each period of moulting, 
for the animal, enveloped upon all sides by a solid and inelastic covering, 
preserves almost exactly the same size up to the moment when its 
envelope is removed, and while awaiting a new covering the body can 
enlarge to but a limited extent. The number of moults is quite consid- 
erable, and is not the same during the same period of time for all indi- 
viduals, for it is known that when placed under apparently similar con- 
ditions individuals of the same brood will vary much in size. Every 
moult is a very critical period for the animal, and a cause of great mor- 
tality, not only because at this time there is a considerable interval when 
the animal is without defense against its numerous enemies, which at 
other times might have been kept away by its hard and formidable 
pincers, or resisted by its firm carapace, but especially because this 
period forms a sort of crisis, occasioned by its increase in size with 
every moult. 
Mr. Coste has shown that the common and rock lobsters change their 
carapace or moult— 
The first year from 8 to 10 times; size then, 0™.04. 
The second year from 5 to 7 times; size then, 0™.09. 
The third year from 3 to 4 times; size then, 0™.14. 
The fourth year from 2 to 3’times ; size then, 0™.18. 
In five years the two forms above mentioned attain a size of 20 cen- 
timeters (about 6 inches), this being the size established by law as the 
smallest that can be caught for the market, and at this time they begin 
to reproduce their kind. After the fifth year, moulting takes place only 
once a year, for, if it were more frequent it would, in the case of the 
female, seriously interfere with the reproductive functions. 
———— 
CAUSES OF THE CONTINUED DEPLETION OF THE OYSTER 
BEDS AND THE IMPOVERISHMENT OF THE FISHERIES. 
What are the causes that have so greatly impoverished the oyster 
beds of our coast, as announced by M. Coste in the report from which 
we have already cited certain extracts? This is the question which we 
propose to discuss in this chapter—a question of prime importance, for 
if it explains the past it also indicates the entire future of the oyster in- 
dustry. The productive forces of nature are so powerful, and the laws 
of general harmony, which preside over the increase and the existence 
of animated beings, are so evenly balanced, that sometimes an apparently 
futile modification in the conditions of development of these beings is 
necessary, in order to give an unlimited range to their reproduction, just 
