14 THE NEW AET OF BREEDING FISH. 



AKTIFICIAL INCUBATION. 



We have seen that in artificial fecundation na- 

 ture has been imitated, where the fish voids its eggs 

 by passing over and pressing its belly against smooth 

 stones. This natural method being imitated by the 

 hand of the operator all the eggs are evacuated with- 

 out the loss of a single one. 



In artificial incubation Mr. Gehin has in like 

 manner exactly imitated nature in the processes he 

 employs. He takes a round box in the form of a 

 warming-pan, except that the bottom rises a little in 

 the inside in order to make it remain more firm in 

 the position in which it may be placed. It is made 

 of zinc to prevent rust ; its size — twenty centimetres 

 in diameter and seven centimetres in depth ; the lid 

 four centimetres in height, on hinges, with a catch. 

 The box is pierced on every side, with two thousand 

 holes, so that the water can freely flow thi'ough it 

 over the gravel. These holes are a millimetre in di- 

 ameter and should be very carefully and smoothly 

 made, with a punch, in such a manner as not to wound 

 the little fish attempting to escape through" them. 



The bottom of the box is covered with a bed of 

 fine gravel, and on this are placed the fecundated 

 eggs. Each box should contain one brood of eggs. 

 The box is then closed, a hole is dug for it in the 

 gravelly bottom of a running stream of fresh water 

 in which it is placed and gravel is strewed over it. 



