ATTITUDES EXPRESSING EMOTION 3 
reveals his suppressed excitement by the movements 
of his tail. If our fox-terrier, going out of the gate, 
suddenly drops on the ground with his head straight 
out in front of him, we can guess he is going to have 
a game with the mongrel next door, and he expresses 
his joy by wagging his tail. Had the dog suddenly 
pulled himself together and advanced on his toes with a 
stiff and stilted gait, the hair on his back erect and his 
tail quivering, it is fairly certain that in a few minutes 
he would have been engaged in a fight. 
The attitudes and movements of the cat and the 
dog convey to us these meanings because we are con- 
stantly seeing them, and if, in the same way, we were 
constantly observing fish, we could read by the move- 
ments of their fins and bodies, and by their changes 
in colour, their intentions and emotions. 
Watch the pike lying outside a reed-bed. He rests 
motionless on the bottom, with his body just off the 
ground, supported on his fins. The muscles of his 
body being relaxed, the line of the back shows a gentle 
curve, and the calm, contemplative state of his mind 
is revealed by the fact that the fin on his back is lying 
flat. That the pike is on the watch all the time is 
evident from the keen look in his eye. Suddenly, 
without any movement of the body or other fins, the fin 
on the back will become erect and fully extended, a sure 
sign of mental agitation. Probably the pike has 
detected a gleam of light in the distance as a dace 
turning on his side reveals his presence. 
