flow to obtain it. 165 
practical work. In water which stands at about 40° to 43° 
.- Fahrenheit ova will hatch in about ninety to ninety-six days, and 
in about forty-two days or a little more the eye spots will begin to 
appear. The time varies a little in the different species of 
Salmonide, and in the case of hybrids is often shorter than in that 
of pure bred fish. The higher the temperature of the water the 
sooner will the eggs hatch, and the colder it is the more they will 
be retarded. Salmon ova have been hatched in thirty days, and they 
have in very cold water been as long as one hundred and sixty days. 
In the year 1883, by using ice freely to lower the temperature 
of the water, I kept some back for a hundred and thirty-two days, 
and by so doing was enabled to have them hatching in my boxes 
at the Fisheries Exhibition at South Kensington on May rath. 
They were the only British ova of Sa/monide in the exhibition. 
They were sent from the Solway Fishery in water in bottles, and 
travelled perfectly. In the warm London water they soon 
hatched, and a few days later I was much amused when explaining 
this to one of the spectators who came to see them. He gravely 
said, ‘‘ Haw, can’t you wepeat the pwocess?” Another seriously 
asked—“ How long a salmon had to sit on its eggs before they 
were hatched?” Surely there is room for some instruction in fish 
culture. ; 
In order to keep the ova ina healthy condition it is necessary 
to run a good current of water over them. The quantity needful 
varies according to the nature and quality of the water. I have 
seen apparently good work done with a small flow ; indeed I have 
myself, in early days, hatched salmon under a tap, from which a 
mere trickle of water came. It is quite possible to hatch ova 
without running water at all, by simply changing it twice daily ; 
indeed, I may go even further, and say that they can almost be 
hatched without water, for I have kept them for many weeks and 
hatched them in damp moss. There are two points to observe in 
carrying out such an experiment—vzz., that there is free access 
for oxygen to the ova, and a means of exit for the carbonic acid 
exhumed ; in other words, good ventilation. But to produce 
really good fish a copious supply of good water must be at hand. 
In the main hatchery at the Solway Fishery there is a supply of 
over two hundred thousand gallons daily, and a similar supply in 
