390 MANAGEMENT OF HATCHING-TKOUGHS. 



(inside) wide, and three inches and a quarter (clear) 

 deep." Each box of the above dimensions will carry 

 from two to three thousand eggs. As will be perceived 

 from the engraving (which represents the hatching appa- 

 ratus at my museum), the boxes are placed one above the 

 other, in such a manner that the water runs from the 

 tap the whole length of box number one, then falling 

 into number two, runs the whole length of that (only 

 of course in the reverse direction). These boxes may 

 be multiplied to any extent one above the other, but I 

 do not like more than six, as when there are many fish 

 in the troughs above, the fish in the lower troughs do 

 not get sufiicient oxygen. The water running from 

 the lowest box should be utilised for the nursery as 

 afterwards explained. 



I am not at all an advocate for hatching eggs on 

 glass bars, the parent fish do not find glass bars at the 

 bottom of the river, but they do find gravel. Gravel 

 therefore should be used for the hatching boxes. Gravel 

 must not be taken from an iron soil ; it should be well 

 washed and even boiled before using ; each piece of 

 gravel should be about the size of a pea. It does not 

 matter whether the gravel is angular or round. Its use 

 in the box is to keep the eggs steady, and assist the 

 young fish in hatching out. Half an inch of gravel 

 in each box is quite sufficient. 



It is advisable to divide off about two inches at the 



end of the box (where the water comes in) with a piece 



of perforated zinc, as this acts as a kind of catch-pit to 



stop any impurities that may happen to be floating 



down the stream. Partitions can also be made in the 



boxes with perforated zinc, so as to pen off the eggs of 



different dates or different species. 



* Hatching- boxes made of slate in sets of three fitted to frame 

 can be obtained from Mr. Edon, Fish Museum, South Kensington. 



