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pregnated eggs in fresh water, when left undisturbed, often 
remain clear throughout the period of incubation, unless con- 
cussion or moving occurs when they may turn opaque and 
white. But in salt water fertile eggs which die become clear 
in the shell, and the embryo, contracted in size, is visible 
within. An egg in this condition, transferred to fresh water, 
becomes white and opaque, but again placed in salt water 
returns to its former transparency, and this alteration upon 
changing the fluid may be seen several successive times, 
Experiment No. 18.—December 15th, 1885, ten of the 
foregoing trout eggs were placed in a tumbler of sea water, 
specific gravity 10199, this was changed daily. December 17th, 
all were dead. 
Experment No. 19.—December 15th, 1885, ten similar 
eggs were placed in a tumbler of fresh water, and treated 
similarly to the last, they remained unaffected. 
Expermment No. 20.—December 19th, 11.55 a.m., dropped 
two live trout eggs from 4 feet height, and placed one in a 
tumbler of salt water, the other in one of fresh. 12.13 p.m., 
egg in salt water became clear at 1 p.m. 12.13 p.m., egg in 
fresh water became opaque by 1 o’clock. 7 p.m., the eggs 
were now reversed, by 8 p.m. the opaque one was clear, and 
the one previously clear was opaque. 9 p.m., the eggs were 
again reversed, and by 10 p.m. the clear one was again opaque, 
and the opaque one clear. 
In the foregoing it was seen that the opaqueness or clear- 
ness of the shell was entirely owing to the character of the 
water (as saline or fresh) in which it was immersed. 
Experiment No. 21.—December 20th, took an opaque and 
dead egg from a hatching tray, and then placed it in salt water; 
it became clear within an hour. 
Closely related to the question of suitability of the water 
for the incubation of the eggs of Salmonide is another as to 
what amount of water can these ova be successfully incubated in? 
or even whether they could be developed without being placed 
in water at all? Here the consequences to the offspring 
(should such be hatched) are not referred to. 
