I. AGRICULTURE AND RURAL ECONOMY. 35 1 



quantity than would naturally be procurable in the immedi- 

 ate vicinity of the imprisoned fish ; but our author considers 

 that all such preparations as chopped meat, clotted blood, 

 etc., are objectionable for many reasons among others, on 

 account of the portion that is not consumed, which sinks to 

 the bottom and remains in the water, rendering it corrupt. 



Dr. Hartmann therefore recommends that if water-plants 

 do not naturally grow in the neighborhood of the nurseries 

 for the fish, they be immediately planted, since these attract 

 and harbor immense numbers of minute insects and crusta- 

 ceans ; and if this be not sufficient, recourse must be had to 

 more distant points. By using fine gauze nets, and sweeping 

 the waters, a vast number of minute animals can be obtained, 

 which are to be turned, while still living, into the nurseries, 

 where the young fish will be found to devour them with the 

 greatest greediness. The rapidity of reproduction of some 

 water-insects is such as to furnish a continuous supply to 

 large numbers of young fish the progeny of a single fresh- 

 water crustacean being multiplied to an almost incredible 

 extent. During the first fourteen days after birth the small 

 water-insects referred to should be the sole food of the brood, 

 as this is the critical period of the nursery. A sufficient sup- 

 ply, according to our author, for 10,000 trout can be obtained 

 in the course of one or two hours by pouring water with a 

 dipper from one of these pools on to a bit of gauze stretched 

 tightly at the four corners. After this, coarser food can be 

 used, especially the larvae of insects, which are readily ob- 

 tained, including the musquito and other diptera. By col- 

 lecting the eggs of frogs and toads, and placing them in 

 pools, they will also furnish food, either directly or after their 

 eggs have hatched out into tadpoles. 



It is also recommended to separate the larger of the young 

 fish from the smaller, as the former are likely to appropriate 

 more than their share of the finer food, thereby retarding the 

 development of the rest. Alluding to the voracity of certain 

 fish, Dr. Hartmann quotes the observations of Coste upon 

 trout, of which four, each an inch long, devoured 6000 em- 

 bryos of perch in* less than five days, or an average of 300 

 apiece each day. 



In rejoinder to the above views by Mr. Hartmann, Mr. 

 Wengen takes exception to the feasibility of obtaining nat- 



