Hatching Fish Ova in Moist Air. 91 



to obviate this difficulty, which cannot arise 

 tinder the moist air system. Another advan- 

 tage of the latter plan is, that any injurious 

 substance which may get into tbe water acci- 

 dentally, and which might destroy the ova, 

 could not affect them in air. The simplicity 

 of the arrangements required for hatching in 

 air is another great advantage, as compared 

 with the elaborate apparatus required under 

 the ordinary system, and a low temperature 

 is much more easily maintained in an air- 

 chamber than with a stream of water. 



The Californian ova above referred to were, 

 on their arrival, found to be packed in netting 

 in a box, between layers of moss, over which 

 a few pieces of ice were placed, and the box 

 had been kept in an ice-house with a uniform 

 temperature of 32 or 33 deg. Of these ova 

 94 per cent, arrived in good condition, and 

 over 50 per cent, hatched out successfully, the 

 hatching having commenced at once when 

 they were placed in the water, and having 

 gone on without interruption till all were 

 hatched, the incubatory process having been 

 almost completed in the moist air of the ice- 

 chamber. 



