SMELL, TASTE, AND CHEMICAL SENSE IN VERTEBRATES. 225 



TABLE II. 



Reaction of Amiurus to Sour, Alkaline, Salty, Bitter, and Sweet Solution! 



Parts 



Reageot 



HCln.. 

 HC1 n/2 . 

 HCln/5. 



HCI n/20 

 HCln/40 



Part of Bodj Stimulated 



Mouth. 



NaOHn 



NaOHn/40. . 

 NaOH n/50 . . 

 NaOH n/100. 

 NaOH n/1000 



Swam backward. 

 Swam away. 



Swam away. 



Mouth movements only 

 No reaction. 



Mid-trunk. 



Na( 1 2n 



Swam backward. 

 Swam backward. 

 Swam backward. 

 Mouth movements only 

 No reaction. 



Swam forward. 

 Swam rarely. 

 No reaction. 

 No reaction. 

 No reaction. 



Tail 



forward 



Swam away. 



NaCl n Mouth movements 



NaCl n/50 Mouth movements 



Swam forward 

 Swam forward 

 No reaction. 

 No reaction. 

 No reaction . 



Swam rarely. 



No reaction. 



No reaction. 



No reaction. 



Swam forward 

 Swam forward 



No reaction. 



No it a lion. 

 No rei lion. 



NaCl n/100 



No reaction. 



Quinine m/10 



Swam backward. 



Quinine m/20 Mouth movements only 



Quinine m/150 Mouth movements only 



Quinine m/200 No reaction. 



Locomotion. 

 No reaction. 

 No reaction. 

 No reaction. 



Cane sugar 2m 



No reaction. 



No reaction. 

 No reaction. 

 No reaction. 

 No reaction. 



■ 



No reaction. 



Locomotion 

 No reaction 



No reaction. 

 No reaction. 



No reaction 

 No reaction. 



No reaction. 

 No reaction 



No reaction. 



As the foregoing account indicates, Amiurus differs from AmnwcmleM 



in 



showing no difference in the sensitiveness of its tail and mid-trunk regions to 

 chemical stimulation and in showing no response whatever to quinine when 

 applied to the trunk and the tail. It agrees with Ammoaztes in not responding 

 under any circumstances to a solution of sugar and in being more aensitiv. in 

 the mouth region than anywhere else. 



4. A Morphological Comparison of the Chemical Senses in 



Vertebrates. 



Having shown that the head, trunk, and tail regions of Ammoaeks and of 

 Amiurus are open to stimulation by relatively dilute solutions of substances 

 such as are stimuli for the sense of taste in the higher vertebrates, it may next 

 be asked what nervous mechanisms serve as receptors for these stimuli, 

 question must be approached experimentally and of the fishes that were studied 

 by me, the only one well adapted to this purpose was Amiurus. The regions of 

 the body of Amiurus that were most favorable for such work were the trunk 



This 



and the tail 



These regions are innervated 



three sets of sensory nerves 



(Johnston, 1906): the spinal nerves concerned at least with the reception of 

 tactile stimuli; the lateral-line branch of the tenth nerve distributed to the lateral- 

 line organs and probably concerned with the reception of material vibrations of 

 low frequency; and the lateral accessory branch of the seventh nerve supplied 



15 JOURN. ACAD. NAT. SCI. PHILA.. VOL. XV. 



