V/HOLESALE BREEDING 65 



sequently it would take longer in the spring to develop a stock large 

 enough for practical use. If possible, it is a good plan to have two 

 or more daphnia ponds, so that one may be replenished while the other 

 is being drawn from. The bottom of daphnia pools should be pre- 

 pared with a substantial layer of dead leaves and manure of any kind. 

 Later in the season, when this has all disintegrated, a new supply 

 should be occasionally added. Any decomposing vegetal or animal 

 substances will do. If a prowling cat has met accidental death by 

 shooting, its carcass placed in the daphnia pond will give quite an 

 impetus to the production of live fish food. For aesthetic reasons it 

 would be well to weight the carcass down with stones. ' 



The plan of this system of pools does not call for running water, 

 but only to admit it as needed. It will be seen that an overflow is 

 provided to carry off the surplus from the tempering pond, this finally 

 discharging into the natural brook from the spring, or into any other 

 place capable of carrying it oft". 



By this plan of having one pool drain into another, instead of 

 discharging into a general overflow, we have an added chance of sav- 

 ing fishes in case of an overflow or accident to the sluices. 



Unless a spring is known to be thoroughly dependable at all times, 

 the possibility of securing water from other sources should be consid- 

 ered in the beginning, particularly as most establishments of the kind 

 now being described are constructed only on clay bottoms, where a 

 certain amount of water is sure to be lost through seepage. 



If the soil has no natural clay bottom, the hole should be dug 6 

 inches lower than the intended depth of pool, say 20 inches in all. 

 Now mix pure clay with water in a mixing box and plaster on bottom 

 and sides to a depth of 6 inches. To secure the sides in this manner 

 they will have to slope gradually. It is better to make the sides of 

 cypress boards and puddle the clay in back of them. These had best 

 be sloped at a slight angle, about 2 inches to a 14-inch board. Even 

 when soil is mostly of clay, there is often serious loss of water near 

 the top on account of the more porous earth. A layer of sand on top 

 of the clay will keep the mud from rising. 



One very important consideration in all outdoor ponds or pools is 

 the possibility of serious loss through freshets. Not only does the 

 pool itself have a tendency to overflow in a protracted downpour, but 

 drainage from higher portions of ground is liable to sweep over low 

 ponds. The latter danger can be overcome by having ample trenches 

 dug on the sides exposed to such risk, and seeing that they in turn 

 drain ofif where the water will do no harm. In regard to direct over- 

 flow, it is a good plan to have screened emergency outlets in each pool 



