294 Journnl of Couipnrntivc Neurology nud PsvcJioJogy. 



'saturated. These results sliow that here as in man the trigeminal 

 ner\T' shares in what we nsnallj call the sense of smell. 



(^iiEZsrifAi. Skxsatiox as a Sense Quality. 



Experiments were next performed to ascertain if these reactions 

 to chemicals are due to the stimulation of nerve endings distinct from 

 those excited by tactile stimuli. First a given region of the body was 

 fatigued for tactile response. One method used was to keep a steady 

 stream of water from a ]>ipette playing on some sensitive portion of 

 the skin. After fi\'e minntes, or such a matter, the fish will no longer 

 respond. Chemical reactions can always be secured thereafter in a 

 little more than the ordinary length of time. When the experiment 

 was reversed, however, the results differ. A given region may be fa- 

 tigued in from five to ten minutes for any kind of chemical stimulus, 

 acids, for example. It will then react to salts, for instance, but not 

 to tactile stimuli for some minutes, if care is taken not to get outside 

 the area fatigued. A blunt point was often used also to fatigue the 

 tactile organs, with the same result. Parker (Y)8b) found in Amjihi- 

 oxus that when the animal was fatigued for mechanical stimuli it 

 still reacted to chemical stimuli, and vice versa. 



Further a 2 per cent, solution of cocaine on absorbent cotton was 

 ap]died to the skin and the region stimulated every few minutes for 

 both tactile and chemical purposes. TTuder these conditions tactile 

 response disappears in from ten to twenty minutes. Tiesponses to 

 chemical stimuli can be ol)tained thereafter, although the reaction is 

 slower than usual. Finally, response to chemicals disappears, the 

 first to cease l)eing that to bitter substances, as is the case in mammals 

 in the mouth, after Addncco and Mosso ('00) and Fontane ('02). 



(ViXCEFSIOXS. 



The results obtained show that the reactions of- the dogfish to 

 substances which we call sour, alkaline, salty, and bitter are ob- 

 tained by stimulation of the nerves of general sensation. One is 

 not justified in saying that the taste buds and taste nerves (the fa- 

 cialis, glossopharyngeus and vagus) do not take part in these re- 

 actions in the mouth. It is certain, however, that such nerves do not 



