' CLAM AND SCALLOP INDUSTRIES 607 



sible, to control the young during its precarious early life till it 

 reaches that stage of development where it is able to care for itself. 



Everyone is familiar with the extensive and remarkably success- 

 ful work of the United States and the various state fish commis- 

 sions in the propagation of marine and fresh-water market fish. In 

 many cases, the continued supply is probably directly and entirely 

 due to the artificial hatching and judicious distribution of the young 

 fish. These institutions have made it very clear that public moneys 

 could not be better expended for the benefit of all classes of people 

 than in their support. Their field is constantly enlarging, also, as 

 one after another of aquatic food animals diminishes in number, 

 and begins to disappear. If the fact were only recognized, that this 

 threatened extinction of forms really is occurring, these commis- 

 sions and similar institutions would receive much greater support 

 in the form of legislative appropriations. More money for carry- 

 ing on the work already attempted is urgently needed, and more 

 still will be required as the field of labor enlarges. At the same 

 time, it is money most profitably invested for rich and poor alike. 



The reestablishment of a destroyed industry which depended on 

 organisms living and reproducing in a natural state, is Usually slow. 

 No one would expect a community depending on wild cattle for its 

 beef to consider the future seriously till the supply was nearly; 

 exhausted. Men seldom look far ahead in such matters. When the 

 extinction is practically accomplished, they cast about for a remedy. 

 The close season suggests itself. But, while waiting for the few re- 

 maining animals to increase to the necessary number, man is neces- 

 sarily deprived of food. Even if the flocks quickly recover theic 

 numbers, because natural conditions for their growth are favorable, 

 the same decrease and destruction is very likely to recur. 



The point is that, when an organism — animal or plant — is largely; 

 used as food by man, nature is most often unable to keep up. the 

 supply indefinitely, and man must breed and cultivate the desired 

 form under controlled, and more or less artificial conditions. 



In our illustration, the habits and needs of the animal — specially 

 the need of food — must be determined, in order that, under confine- 

 ment, a maximum rate of reproduction may be obtained. In ad- 



