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in clear water, but the eyes of the former were much smaller 
than those of the latter. 
The question of the depth of water in which eggs will hatch 
is not an unimportant one, because it is asserted that in Salmon 
rivers fish which ascend late to deposit their spawn, root up the 
nests of the first comers. The experiments instituted by the 
author go to prove conclusively that a depth of at least 26 
inches does not injuriously affect the hatching of the fry. 
It has always been a disputed point as to the amount of 
water which is necessary for incubating these eggs in. In such 
as are conveyed to Australasia it is done in a chamber cooled 
by ice, the eggs themselves being in boxes packed in layers of 
moss, where it is evidently impossible they could be immersed 
in water, yet the embryos live and develop, providing the recep- 
ticle is sufficiently damp, cold and dark. 
The last subject experimented upon was concussion, first as 
to the effect of slight shocks, next as to severe ones, and lastly 
to the age of the embryo at which they had been tried, and 
with this result, that although it was evident that in their 
earliest stage, or during the first 24 hours, the impregnated 
ovum would stand movement, this capability became subse- 
quently less, and did not return until at least one-third of the 
period of incubation had passed. But although eggs may be 
hatched under very adverse circumstances, this does not show 
that the young will be of a strong constitution, while, after 
hatching, an increased depth of water is necessary to rear them 
in. This requirement for space is one of the reasons for con- 
sidering it to be of very doubtful benefit in incubating eggs in 
trays placed one above another, for, even should the young 
hatch, the amount of tray-room would subsequently be insuf- 
ficient to accommodate all the progeny without crushing, which 
would probably dwarf the offspring. 
It does seem rash to turn all the young so soon as they have 
absorbed their yolk-sacs into a main stream, whereby all 
trace of them becomes lost, and where the majority will 
die or be devoured by their enemies. It would, with few 
exceptions, appear best to retain these fish until at least a 
