ARTIFICIAL BREEDING OF SALMON. 2.03 
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 aérated, 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 has hatched ova in damp moss, 
without even immersing them in water at all! 
