PROPAGATION OF FISH. 261 



the eggs may be too large for extrusion in case the male 

 parent is the larger variety cf fish, and the other that 

 the entire body of one hatching may be of a single 

 sex as in this case when all were females, and in the 

 case of the shad and herring in the Hudson Eiver, which 

 are all said to be males. It was'on these two discoveries 

 that subsequent improvements were founded. It is not 

 yet positively determined that these cross-breeds will pro- 

 create their species in a natural way, nor even that they 

 will be the improvement, which has been hoped, but that 

 they can be bred artificially there is no further doubt. 



An indirect result of fish-culture has been the intro- 

 duction of foreign fish into home waters. The German 

 carp has been brought to America, and has increased and 

 multiplied vastly, and been found well adapted to certain 

 waters, which are not valuable for finer fish. In dull, 

 muddy, small ponds, they have not only lived, but they 

 have grown to a remarkable size. We have also received 

 some German trout, which hatched and grew well, and 

 which promise finely for the future. Then we have sent 

 our black-bass to Europe as well as our trout, the Califor- 

 nia trout and salmon. "We have acclimated in California 

 the Eastern shad, and imported from California the trout 

 and salmon of that country. This interchange has been 

 mutually advantageous and promises to be much more so 

 in the future. The results of fish-culture have indeed far 

 exceeded the most sanguine hopes of those who first took 

 it up, and at present there seem to be no limits to its ben- 

 eficial effects. The time will surely come when the 

 streams, which have been so long utterly depopulated of 

 their natural inhabitants will once more be restocked and 

 yield as abundantly as ever. This has already happened 



