182 How to obtain it. 
extent, more favourable for the use of such an apparatus, than the 
comparatively higher one in this country. But whatever be the 
reason, I am satisfied of one thing, and that is, that the grille 
system is the one of all others for successful work in Britain. It 
gives the eggs plenty of room, and removes all danger of suffoca- 
tion where a good current is run over them. The carbonic acid 
given off by the egg is at once carried off, and the absorption of 
the oxygen from the water is unhindered. 
In Germany, perforated glazed pottery is used extensively for 
hatching ova upon, and, with the water welling up through the 
perforations, it does very good work. It has its objections, 
however, those of cost and liability to breakage being not the 
least. A broken tube in a grille is easily repaired, or replaced, 
but not so with a piece of pottery. To repair a broken tube, all 
that is necessary is to insert a piece of charred wood, cut to the 
proper size, into one of the broken pieces, so that half of it 
remains projecting. Then slip the other portion of the tube over 
this projecting piece, and the tube is again ready for use. Grilles 
can be made of ordinary window glass cut into strips, and fitted 
into a cogged or notched wooden frame. The cost of making the 
frames, seeing that every cog has to be separately charred, is 
considerable, and it is on this account chiefly that they have fallen 
into disuse. A few still remain in operation in my own hatcheries, 
and considering only the hatching of the ova they do quite as 
well, if not better, than the more modern arrangement of glass 
tubes or rods. It has been suggested that the rough edges of the 
lass will cause injury to the ova, but this is by no means the case. 
I have hatched many millions of ova most successfully on these 
grilles, and have found them to work very well indeed. The 
advantages of the more modern invention are that they are a 
little easier to make, and the glasses are not so apt to fall out, and 
those who have to use them prefer them to the old style. 
One of the chief things to be avoided in a hatchery is the 
overcrowding of the eggs. It should never be permitted under 
any circumstances. J have tried a number of experiments with 
ova, with a view to economising space when necessary, and many 
years ago, before baskets and cages were thought of, I invented a 
hatching-box, in which several grilles can be placed one over the 
