Flow to obtain it. 177 
to remain, whether they like it or not; but from the artificial bed 
they can escape at any moment that they may be seized with a 
desire to go. Indeed, perfect freedom is the secret of the whole 
thing. The little fellows have no recollection of having been 
shovelled about as eggs, and counted, and incubated on glass 
grilles. They find themselves in a very natural and tidy-looking 
place, and are content with their surroundings until a desire seizes 
them to roam, and when this occurs they must find themselves at 
perfect liberty to do so. 
In addition to the dug-out system and the wooden one, both 
of which possess the advantage of being ready at very short notice, 
excellent work of a more permanent nature may be done by using 
concrete or brickwork. In this case, however, the work should 
be done in June or July, and the water turned on a few months 
so as to have everything well seasoned before hatching time. 
Cement is partially soluble in water, but this only applies to the 
time when water is first run over it. The soluble portions are 
soon taken up, and the face of the concrete becomes coated with 
a vegetable growth; after this it does no harm. The great ad- 
vantages of these hatching beds are that they can be made available 
for use at once; that when once started no one has to attend to 
them ; that they cost very little and do a great deal; they can be 
fitted up in a day, or a couple at most, on any stream, and the 
results are certain if good eggs be laid down. It should always 
be borne in mind that both ova and ‘“alevins” should be kept 
well shaded from light. A box with a lid on is good, but the bed 
made in an open ditch must also be covered. A few old boards 
will come in very useful here. I have found larch slabs battened 
together do admirably, look neat and rustic, and last for years. 
Only one thing more is needful for the successful working of 
an artificial ova bed, and that is an unfailing supply of water. I 
do not mean so much in the sense of quantity as in certainty. 
There must be no doubt as to whether the supply will continue. 
No choking of the screen or entrance of a frog into a tile must 
be allowed to cause a stoppage of the works. These things are 
easily guarded against, and proper precautions must be taken from 
the first to prevent such calamities. A very simple way of dealing 
with the water at the intake is to have a sufficiently large screen 
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