80 FISH CULTURE. 



this metal hardened with tin. This woidd keep 

 the gravel in its place, and prevent it from shifting. 

 The ova -would thus be kept deep and safely in the 

 gravel for a fortnight or more. I would also employ 

 ice freely to keep down the temperature of the water, 

 and retard the hatching as much as possible, as 

 every day gained is a day gained from the foul 

 weather usually encountered in the Channel and the 

 Bay of Biscay at the time of year when such experi- 

 ments must be made. Light is disadvantageous to 

 the ova as well as to the hatched fry, and I would 

 therefore erect the apparatus in the hold, as near 

 the keelson and the centre of the vessel as possible, 

 there being less motion there, and space being of 

 comparatively far less value than between decks ; 

 added to which, neither apparatus nor superinten- 

 dent would be in the way in heavy weather, as they 

 are pretty sure to be in any other part of the vessel, 

 so that all operations could be conducted without 

 let or hindrance. The ova might be kept from hatch- 

 ing by a plentiful supply of ice for from a fortnight 

 to three weeks, and by that time comparatively fair 

 weather might be expected. Let us suppose the 

 ova hatched in the secure little chambers in which 

 they were deposited. Some few of the fry might 

 come up above the gravel ; they, of course, would 



