166 W. J. CROZIER 
The delicate sensitivity manifested in the responses of the 
blind hamlet upon the near approach of foreign objects is there- 
fore not induced by the absence of the eyes or by procedures in- 
cidental to their removal; it is present in the normal seeing fish, 
although reactions to which it might give rise are largely inhib- 
ited through visual and coarse mechanical stimulations (touch). 
It is obvious that this form of irritability, if present but unrecog- 
nized, might lead to serious errors in the interpretation of differ- 
ent phases of behavior not only in the hamlet, but also in other. 
fishes where it may occur. 
~2. De-eyed hamlets, stationary in mid-water or slowly swim- 
ming, but not in contact with the bottom or walls of the aquarium, 
were found to show the following regional distribution of sensi- 
tivity to the gentle approach of the rounded end of a clean 
glass rod (3 mm. diameter): tip of the snout, side of head, caudal 
peduncle, top of head, side of body (especially in the region cov- 
ered by the pectoral fin when it is folded back on to the body), 
anterior edge of the erect spinous dorsal fin, soft dorsal fin, 
caudal fin (except near its distal extremity). 
The parts are arranged in the foregoing list according to the 
vigor of the reactions induced. No well-defined responses could 
be secured from the ventral surface of the animal nor from the 
pectoral or pelvie fins. The nature of the response varies with 
the different regions of the animal; thus, the spinous dorsal was 
pulled down close to the body when its anterior edge was 
approached, while the soft dorsal responded by vibratory 
movements. 
About twenty-five individuals were carefully studied to de- 
termine the distribution of this sensitivity to ‘contact at a dis- 
tance.’ The critical tests were made in filtered ‘outside’ sea- 
water (the circulating water of the laboratory being less alkaline 
than normal sea-water), and the conditions were so arranged 
that no shadows from the body of the experimenter or from the 
glass rod fell upon the surface of the fish. These tests were 
made upon single isolated fishes in non-running water. 
Rods or wires of a number of different materials were found to 
induce reactions of this type. In all cases the rods were well 
