THE SENSES OF A TROUT 89 



uncanny quickness of trout in discovering my vicinity 

 under these conditions completely baffled me, but curiously 

 enough the explanation came to me when bathing in the 

 Ifafa River, Swaziland. I had been swimming in just such 

 a pool as I have described, and had drifted to the lower and 

 shallow end. My body was resting on the pebbles, and my 

 eyes were just above the water gazing up-stream, when my 

 attention was drawn to a distinct lessening of the light on 

 the pebbles in front of my eyes, and slowly turning my head, 

 I found two Reit buck standing on the bank of the river a 

 little distance below me, and silhouetted against the clear sky, 

 from which position they had appreciably lessened the light 

 falling on the pebbles. Their curiosity had evidently been 

 aroused, and they appeared to be looking at me intently. 

 I did not move, but something frightened them, and they 

 turned and bolted out of sight. The incident, however, 

 solved the difficulty. 



In shallow, pebbly pools the trout lie immediately over 

 the glistening and reflecting surface of the pebbles. Any 

 object, therefore, which comes between these pebbles and 

 the sky must shut out some of the light which falls on them, 

 and this lessening of the light they reflect must warn the 

 trout that some object is moving or approaching them from 

 down stream, and hence their movement up stream. 



HORIZONTAL SIGHT 



If the eyes are assumed to be the centre of the horizontal 

 plane in which the fish is lying, a trout, in ordinary 

 condition, can see in that plane from a point right ahead to 

 an angle of about sixty degrees behind each shoulder. In 

 other words, any object situated in the 300 degrees of 

 the forward part of the horizontal circle surrounding 

 a trout, will, as a rule, be visible, while any object situated 

 in the remaining sixty degrees of that circle would be 



