ARTIFICIAL BREEDING OF SALMON. 203 



be remembered that every fertile egg contains a living 

 being, which requires a constant supply of air for 

 its preservation, and that the quantity of air contained 

 in a confined vessel is more rapidly consumed by the 

 ova than fresh air can be absorbed from the surface. 

 The consequence will be that unless fresh water be con- 

 stantly supplied, or the water in the vessel be by some 

 means aerated, the embryo contained in the egg must 

 die. But not only will the constant replenishing the 

 vessel with fresh water be troublesome, and often im- 

 possible, but will also be attended with great risk to the 

 safety of the ova. 



If it is borne in mind that it is not the water, but 

 the air which is therein contained that is essential 

 to the preservation of the ova, it will be apparent that 

 if they be kept moist, and have a constant supply 

 of fresh air, the necessary conditions will be obtained. 

 The readiest and easiest way is to pack them in damp 

 moss (the marsh moss, Sphagnum, which absorbs 

 moisture like a sponge, is the best), through which the 

 air will readily circulate.* 



In a common wooden box the moss will retain its 

 dampness so as not to require wetting for several days. 

 And indeed caution is requisite when it is so sprinkled 

 that the temperature of the fresh water be not lower 



* Professor Rasch told me that he lias hatched ova in damp moss, 

 without even immersing them in water at all ! 



