MANUAL OP FISH-CULTURE. 261 



growth, hence the desirability of selecting- a shallow pond. The yonng 

 should be separated from the adult frogs during this time, as they are 

 eagerly eaten ; and it is needless to say that the pond must be free 

 from fish, turtles, snakes, and crayfish. 



The critical period occurs at the time of metamorphosis. The crea- 

 ture is now abandoning its aquatic habits and has not yet a perfect 

 apparatus for terrestrial life. Any slight disarrangement of the natural 

 environment is liable to destroy the equilibrium. The rapid resorption 

 of the tail furnishes matter for growth, so that food is not so much a 

 necessity, but as soon as the terrestrial habit is fully assumed live food 

 is absolutely requisite, and should be furnished in liberal quantities. 

 There seems to be no reason why this might not be accomplished by 

 transfer of the tadpoles to waters where natural food abounds. It is 

 useless to attempt to supply this food artificially by any method at 

 present known, neither has any device to increase the natural abundance 

 of insects been practicable as yet. The pond should have a growth 

 of rushes and other plants; wild rice {Zizania aquatica) has been recom- 

 mended, but it might attract birds that would prefer young frogs and 

 tadpoles to their vegetable fare. Shade is necessary. Such a pond 

 will furnish natural food for a large stock of frogs, and give opportunity 

 for successful breeding. 



One of the most successful " frog farms " is in Ontario, in the Trent 

 Kiver basin. It has been in operation about twenty years and annually 

 yields a comparatively large product of frogs. The waters were stocked 

 by means of mature mated frogs. No attempt is made to confine the 

 frogs until near the time for shii^ment to market. They are then taken 

 alive at night, with the aid of a torchlight, and confined in small pens 

 that can be drained when the frogs are desired for market. No food is 

 given, as this is naturally present in sufficient amount for successful 

 growth. The species is the eastern bullfrog {Rana catesMana); it 

 begins to breed at the age of three years and reaches a marketable size 

 in four years. During the years 1895 and 1896 this "farm" yielded 

 5,000 pounds of dressed frog legs and 7,000 living frogs for scientific 

 purftoses and for stocking other waters. 



While at present it would perhaps be advisable to limit practical 

 attempts at frog-culture to stocking natural waters with paired breeders, 

 experiments in artificial methods should not be abandoned. There 

 seems no reason why methods similar to those at present pursued in 

 fish-culture may not eventually be successful in the case of frogs. 



