304 G. E. COGHILL 



cedes, are probably ''not at all due to sensory stimulation by 

 acid?" 



7. Granting that the so-called chemical stimuli act indirectly 

 through the epithelial cells upon the nerve endings mechanically, 

 may not the api)arent physiological separation of the tactile 

 and chemical receptors by use of cocaine still be accounted for 

 upon the basis of the comparative strength of stimuli (Coghill, 

 '14, pp. 206, 207)? 



8. Regarding psychological differentiation of the two forms 

 of stimuli as applied to the inner surface of the cheek of man, 

 are the components of the cranial nerves of man sufficiently 

 known to warrant the inference that morphologically equivalent 

 receptors are concerned in the oral cavity of man and in the skin 

 of the fish or frog? May not the visceral sensory system be 

 a factor in the irritability in the oral cavity? 



Some of these questions I have under investigation and I 

 shall probably discuss them further in a later paper. Meantime, 

 in the interest of the leading problem of my investigations, I 

 shall hope to see Crozier's methods of inquiry projected further 

 into the question concerning the existence of a 'general chemical 

 sense' in the skin of vertebrates. 



