74 THE OYSTER. 



nel, at one time afforded employment to 400 vessels. 

 In six or seven years the dredging became so exten- 

 sive and the beds so exhausted that only three or four 

 vessels could find employment, and the crews of even 

 that small number had to do additional work on shore 

 in order to support themselves. 



In view of such facts as these, no one who appreci- 

 ates the magnitude of the oyster industry of the 

 Chesapeake Bay can doubt that the protection of our 

 beds is a matter of vital importance, for it is quite 

 clear that we cannot trust to the natural fecundity of 

 the oyster. 



It is well known to naturalists that the number of 

 individuals which reach maturity in any species of 

 animal or plant does not depend on the number which 

 are born. The common tapeworm lays hundreds of 

 millions of eggs in a very short time, yet it is com- 

 paratively rare. The number of children born to each 

 pair of human beings during their lifetime of sixty or 

 seventy years can be counted on the fingers, yet man 

 is the most abundant of the large mammals. The abun- 

 dance of a species is mainly determined by the ex- 

 ternal conditions of life, and the number of individuals 

 which are born has very little to do with it. 



In the case of the oyster, the adult is well protected 

 against the attacks of most of the enemies which are 

 found in our waters, by its shell, and as its food is 

 very abundant and is brought to it in an unfailing sup- 

 ply by the water, it is pretty sure of a long life after it 

 has reached its adult form, but the life of the young 

 oyster is very precarious : that of the young American 

 oyster peculiarly so, since it is exposed to many 



