606 IMPREGNATION OF EGGS IN TROUT BREEDING. 
Figure 121 represents a small spawning box with a portion 
of the side removed. Figure 125 is an enlarged view of the 
front of the same box. At A is seen a double row of 
frames each two feet square with a bottom of coarse wire 
cloth. Instead of being made singly they are put together 
in one piece. These screens are to be filled with coarse 
gravel and the eggs pass through as in Ainsworth’s screens. 
Under these is an endless apron of fine wire cloth, D, pass- 
ing over rollers at the two ends of the box. This apron is 
about one inch beneath the upper screen, and is kept from 
Fig. 124. 
Roller Spawning Box, 
sagging by small cross-bars (two of which are seen in the 
cut) corresponding to the divisions of the upper screen. 
These cross-bars are supported by and, when the rollers are 
turned, slide on an inch square strip nailed to the side of the 
box. A similar strip one inch above supports the larger 
screens, 
The eross-bars also keep the eggs from being carried 
down by the current. By using two small beveled cog-wheels 
the front roller can be turned by the handle seen at G. As 
the roller is turned forward the endless apron moves with it, 
and the eggs as they come to the edge of the roller will fall 
off. The pan, C (fig. 125), is placed in front of the roller, 
and receives the eggs as they fall. The box need not be more 
