* BULLETIN OF THE UNITED STATES FISH COMMISSION. 209 



Vol. V, Wo. 14. Washington, D. €. Aug. 7, 1885. 



52.— NOTES OIV CARP AM> FROG CULTURE. 



By JOHN II. BRAKELGY. 



Two excellent plants for a spawning pond are the azolla and the 

 water-chestnut. 



The azolla. — This is a small cryptogam, with minutely imbricated 

 leaves, and fibrous roots freely floating in the water. These little 

 plants multiply rapidly, and early in the season will cover closely, as 

 with a beautifully variegated carpet, considerable portions of the pond 

 near its margin. They thus become suitable hiding-places for the dif- 

 ferent varieties of protozoans, where the latter find partial protection 

 and have a chance to multiply. Later in the season I have frequently 

 noticed the youug carp working among the floating roots, evidently in 

 pursuit of food. Besides their furnishing excellent pasture grounds for 

 the young fish, they are decidedly ornamental. When growing in the 

 shade their color is a rich green of various tints, while where they re- 

 ceive the full sunlight they are a beautiful purple. 



The watee-chestnut (Trapanaians). — This is also a floating plant, 

 but with much longer roots than the azolla, so that it does not move 

 about readily in the water. It is a phenogamous plant, but with an 

 inconspicuous flower, its beauty consisting in its foliage. Though a 

 native of India, where it is said to be largely cultivated for the nuts 

 which it produces and which are used for food, it grows well in the 

 ponds of our Middle States. The leaves are of rich deep green, with 

 scalloped edges, floating in the water and forming a compact mass some 

 10 or 12 inches in diameter. It can be grown among other water-plants 

 with very fine effect. It does well in water from 1£ to 2 feet in depth, 

 sending its fibrous roots nearly or quite to the bottom. The nuts, about 

 the size of an ordinary chestnut, are formed beneath the leaves, and 

 when not gathered fall to the bottom of the pond. There they remain 

 till the following spring, when, in due time, the delicate, graceful leaves 

 make their appearance above the water. The fibrous roots doubtless 

 furnish an abundance of shelter, where water animalcules may hide and 

 multiply, which they do with immense rapidity under favorable cir- 

 cumstances. In a pond warmly located and supplied with only enough 

 water to make up the loss from evaporation the multiplication of these 

 little denizens of the water is simply wonderful. It is said that one 

 female cyclops will be the parent of over 4,000,000,000 in a single year. 

 AYhile many of these small creatures are eaten by the carp, others be- 

 come the prey of the larger water larvae, which eventually also become 

 Bull. TJ. S. F. C. 85 14 



