604 IMPREGNATION OF EGGS IN TROUT BREEDING. 
of the hands in cold water in the middle of winter is not 
very desirable, and if this has to be repeated a half dozen 
times every day, it becomes a thing to be avoided if possible. 
Then, too, all the fish in the race have to be taken at the 
same time, whether ready or not; and the interruption to 
those who are just commencing to spawn is bad for many 
reasons besides the danger of handling them two or three 
times to see if they are ripe. These disadvantages and es- 
pecially the first mentioned, induced Mr. Stephen H. Ains- 
worth to prepare and use what are known as the " Ainsworth 
Screens.” This invention is an imitation of a natural trout 
bed. Coarse gravel is placed in a wooden frame two feet 
square and three or four inches high with a bottom of wire 
Screen eoarse enough to permit trout eggs to pass through 
readily. A similar frame with sides only one inch high and 
fine wire bottom is placed beneath the first, and both are 
sunk eight or ten inches in the raceway. Trout making their 
nests in the boxes lay bare the coarse screen. The eggs; 
being at the same time impregnated by the milt of the male, 
fall through the meshes of the upper screen and are caught 
and retained by the fine meshes of the under sereen. The 
two frames fitting closely together make it impossible for 
any fish to get at the eggs, and they are kept safely until the 
screens are removed and the eggs taken to the hatching 
house. The advantages of this plan are very great; but 
they are obvious and may be summed up in a few words. 
There is no danger by this method of getting unripe or 
immature eggs, as the eges are all naturally spawned. It is 
also certainly reasonable to suppose that a fish can do this 
part of the- business best. There is also no danger of loss 
from handling the fish; and a comparative novice can take 
the place of a more experienced hand. Then in this way 
the fish select their own partners; and probably when left to 
themselves those pair which are best adapted to each other; 
whereas in the stripping process, the pairing is arbitrary and 
no rules for selection are known. 
