TACTILE RESPONSES OF DE-EYED HAMLET ike al 
By several stimulations in rapid succession the vigor of the 
response elicited upon the near approach of a glass rod may be to 
some extent heightened. Such reactions are never so vigorous as 
those ealled forth by acid or alkali. If, however, tactile stimu- 
lation by this means be induced immediately after relatively 
severe chemical irritation (n/10 HCl from a pippette), it is found 
either that the local irritability is quite unaffected or that it is 
slightly decreased. With weaker acid, inducing, nevertheless, 
very vigorous reactions, no effect could be detected upon subse- 
quent excitability by the near presence of glass rods or wires. 
The results of the test thus briefly outlined are uniformly in 
agreement with the idea that (within physiological limits) the 
excitation of the ‘common chemical sense’ has nothing to do 
with tactile receptors or with the destruction of the epithelium, 
since the delicate form of ‘touch at a distance’ employed in the 
de-eyed hamlet shows no specifie effects of a sort otherwise to 
be expected when the receptive areas of this sense are bathed with 
chemical excitants. These results make it impossible to sup- 
pose that acid, for example, could disorganize the skin (as sug- 
gested by Coghill) sufficiently to induce violent painful excita- 
tion and yet at the same time leave sensitivity to minute mechani- 
cal disturbances practically unaffected. 
And if acid acted directly upon tactile receptors, it would be 
expected that organs of delicate tactile receptivity would behave 
toward subsequent mechanical activation as if they had recently 
been activated; as previously described, this is apparently not 
the case. It might be objected that the source of stimulation 
could not, in the ‘tactile’ experiments with wires and rods, be 
localized with sufficient precision for critical use. Yet this would 
be incorrect, as could very nicely be shown in tests made upon 
small narcotized areas of the skin. Regions (on the caudal pe- 
duncle) not more than 2 em. in diameter were painted with cocaine, 
and when the pale anaesthetized part was approached with the 
end of a thin rod, no reactions followed, although similar spots 
3 cm. away were of fully normal sensitivity. 
This result confirms the conclusion which I supported in a pre- 
vious paper (716), to which Coghill (’?16) has made further and (it 
