164 W. J. CROZIER 
by the blind fish. When a clean glass rod is carefully and very 
slowly brought near one side of the head, say to within 4.5 or 5 
em. of the gill cover, the fish bends in the opposite direction and 
swims slowly backward; or it may back deliberately away for 
10 or 15 em., then abruptly turn away from the side stimulated 
and assume a position at right angles to that held before being 
stimulated. When one side of the caudal peduncle is stimulated 
in this way, the tail is caused to bend away from that side, and the 
fish swims forward and usually turns in a complete half-circle 
away from the area of activation. 
Unblinded fishes, when not resting on the bottom, usually give 
somewhat similar responses, although rarely so if any region 
other than the anterior end is being ‘stimulated’ by the near 
approach of a glass rod. With de-eyed individuals the best re- 
sults are obtained when the fish is quietly swimming or is sta- 
tionary in mid-water. As noted by Jordan (’17, p. 447), the 
normal hamlet usually les on the bottom of an aquarium, par- 
ticularly in the angle between a wall and the base of the con- 
tainer. When in the latter position, the hamlet does not usually 
react by body movements to the close approach of a glass or 
metal rod, although eye movements and increased vibrations of 
the pectoral or other fins may show that the foreign object is 
seen and perhaps also sensed in some additional manner. It 
frequently happened that responses of the kind described were 
not obtained from totally blinded hamlets when they were in a 
similar position; that is, when they were resting in a corner of 
the aquarium. 
This applies also to hamlets from which only one eye had 
been removed; animals so prepared characteristically seek a 
corner of the aquarium?—a dark corner, if such be available— 
and for long periods remain in a fixed position with the side 
° The aquarium used in most of these experiments was that already described 
in Jordan’s paper (717). It had solid wooden ends and plane glass sides. In 
working with hamlets having one or both eyes functional the arrangements were 
such that the experimenter was screened from the fish, and the glass, or other, 
rod was suspended from above and moved about by an appropriate arrangement 
of strings. 
