170 W. J. CROZIER 
minals representing a ‘common chemical sense,’ are in reality 
due to the heterologous activation of tactile and pain terminals, 
owing to destruction of the epithelium, then it would be expected 
that the local application of irritants to the skin of the hamlet 
would produce one of two effects; either tactile sensitivity would 
be noticeably increased immediately thereafter or, following 
relatively severe treatment, it would be found more difficult to 
bring about tactile activation. In the former case it might be 
held that excitants for the ‘eommon chemical’ sense are capable 
of acting upon tactile receptors in a sensory way. — 
In testing this matter, my experiments dealt mainly with the 
areas of skin on @ther side of the caudal peduncle, although other 
regions were also examined, notably, the lips and gill-covers. 
In different individuals these areas were treated with solutions 
of cocaine hydrochloride in sea-water by painting the surface in 
question (held out of water) with a brush. The dermal chromat- 
opores in the region cocainized quickly contract and remain con- 
tracted for some hours. The area treated is sharply outlined 
by the blanching of the skin. The narcotized area is thus 
clearly delimited for reference in stimulation trials. 
Even slight cocainization causes a complete suppression of the 
sensitivity to rods or wires, as well*as to water currents; slightly 
stronger narcosis obliterates all responses to touch. Even then, 
however, the anaesthetized surface is fully active in the reception 
of stimulation from acid and alkaline solutions (HCl, NaOH, 
NH,OH, n/20-n/40) or from dilute solutions of quinine. The 
sensitivity to delicate mechanical stimulation in these experi- 
ments returns with equal rapidity whether or not the narcotized 
area has been stimulated chemically while under anaesthesia. 
The hamlet, normal or de-eyed, reacts to local treatment with 
n/20 NaOH or NH,OH on the caudal peduncle after the spinal 
cord has been transected, but this operation obliterates the sen- | 
sitivity to minute mechanical disturbances at all levels poste- 
rior to the cut and decreases the amplitude of responses of this 
nature in other regions. 
+A view suggested also by Watson (714, pp. 419) and apparently accepted in 
some degree by Herrick (’16, pp. 85). 
