Flow to abtain it. 171 
of its existence 80,000 eggs, at a cost of less than three farthings 
per thousand, and the work, other things being equal, is done 
satisfactorily. 
Glass gives off nothing, is easily kept clean, and does not 
require any varnish. Metals, such as are used, are at least 
partially soluble in water, and in some waters are very soluble 
indeed, and this renders necessary the use of varnish. A care- 
fully prepared compound does very well, but some varnishes 
contain highly injurious ingredients, and here again is a con- 
siderable source of danger. Notwithstanding all drawbacks, 
however, I believe very good results have been obtained by using 
metallic trays. 
I was one day discussing this matter with an American fish- 
culturist, who assured me that they had discarded grilles long 
ago, and he exhibited to me, and explained, some of the metallic 
trays and baskets that were in use in the United States and 
Canada, and said to be doing very good work there. In reply 
to the query, as to which system would shew the heaviest death- 
rate, he at once replied that probably it might be a little greater 
on the metal than on the glass. His reply confirmed my con- 
victions, and decided me all the more in favour of the glass 
system. I have since experimented myself, and have also had the 
benefit of the experience of others, and can only come to one 
conclusion. It is, that there exists at least one very great 
advantage in the grille system over every other, viz.that stronger 
and better developed embryos are produced, and they have a far 
better chance of growing up and making good fish than any 
others. 
The counting of the eggs, too, isso easily done on grilles, that 
in a large hatchery they are found not only a great convenience, 
but a great saving of labour. They also ensure correctness in 
estimating the number of ova laid down. ‘The eggs arrange 
themselves so readily in rows that in a few minutes a large 
number of them may be accurately counted. For instance, a 
grille contains a hundred rows of eggs, and there are forty in a 
row. When multiplied this gives four thousand as the contents 
of the grille. A box contains ten grilles, which means forty 
thousand of those particular eggs. In another hatching box are 
