224 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
After the eggs have been impregnated, it is the custom to pour more water in the 
pan in a few minutes, and then leave the eggs xjerfectly quiet until they separate, which 
in the Avater of McCloud Eiver in September (52° to 53° F.) usually takes about an 
hour. It should be added that the pans of imiiregnated eggs are jdaced in a trough 
filled with river water to keex) them from becoming too warm. After the eggs separate 
they are carefully washed from all x>articles of effete milt, and then carried in buckets 
to the hatching-house. Here they are measured and placed in the hatching-trays. 
HATCHING THE EGGS. 
At Baird station the Williamson troughs with deep trays have been used for 
hatching the eggs. This xilan has been found to be, in the writer’s judgment, the best 
thing yet devised for maturing salmon eggs on a large scale. The trays used are really 
wire-netting baskets, about 12 inches wide by 24 inches loug, and deej) enough to bring 
the top of the trays an inch or two above the water, which is 5 or 6 inches deep in the 
Williamson troughs in which they were jdaced. Into these trays we iiour 2 gallons of 
salmon eggs at a time. This makes the eggs 12 or 15 tiers deep, and yet they suffer 
no injury whatever from being so jiiled uji, one explanation of this being that the 
water all the time forcing its way up through the eggs loosens them so that they do 
not feel the weight of those above them, while at the same time it reaches every egg 
and furnishes a fresh supxily of air to them all. 
The advantages of this method are: 
(1) The top of the tray or basket is out of the water and always entirely dry; 
consequently in handling them the hands are always dry. 
(2) By tilting one end of the tray or basket ux) and down a little, or by lifting the 
whole basket and settling it gently back again in its x^lace, the white eggs will be 
forced to the top. Consequently no feather is required in x>ickiug over the eggs, and 
thus the injuries very often inflicted vdth the feather are obviated. 
(3) The tox> of the basket being above the water, the eggs can never run over the 
tox> nor escaxie in any way, which is a great advantage over the shallow trays. 
(4) The whole thing is so simple that nothing simxiler that answers the purpose 
can be conceived. There is no coinxilication of xiarts. There is nothing, in fact, to 
look after or move but the basket itself. 
(5) Finally, it economizes sxiace. Fifty thousand eggs can be kexit on a super- 
ficial area of 2 square feet. Two troughs 20 feet loug and 1 foot wide will, by this 
method, carry 4,000,000 salmon eggs. 
The sx>ace in this trough, as in other hatching-troughs, is divided into compart- 
ments a trifle longer than the trays that are used to contain the eggs. The xieculiar 
feature of the trough is that at the lower end of each compartment a cleat or xiartition, 
extending entirely across the trough, reaches from the bottom almost to the tox>, and 
another similar xjartition at the ux)per end of the comxiartment reaches from the tox> 
almost to the bottom of the trough. The water is consequently forced to flow under 
the ux)x>er partition and over the lower xiartition, and in order to do this it must neces- 
sarily ascend through the trays of eggs. 
Two results are secured by this method : 
(1) The trays may be made several inches deexi and may be filled at least half 
full of eggs. 
(2) A good but gentle circulation is continually maintained through the eggs. 
