2/6 Jonriinl of Comparative Neurology and Psychology. 



pliibia by means of solutions of ditferout clieinicals. The selachians 

 were very sensitive to weak stimuli, reacting to dilute solutions of 

 vanillin all over the body, but to quinine only about the head. Bar- 

 bus failed to react to salty, sweet, bitter, or sour substances on the 

 general body surface, while Gasterosteus reacted to quinine only about 

 the head. With Cobitus and Gobius he obtained reactions with 

 meat juice and sugar solutions. Lo])hius was sensitive to chemical 

 stimuli over the entire skin. Triton, the only amphibian tested, re- 

 acted on stimulation of the head only. It is evident from later work, 

 particularly that of Hcrrick ('():>, '03c) and Parker ('07, '08a, '08b), 

 that Nagel's i-esults did not permit the drawing of sound conclusions, 

 partly because of the su1)stances used as stimuli, and partly because 

 he failed to ditferentiate Ix'tween fishes with taste Imds on the outer 

 surface and those lacking such structures with their visceral sensory 

 innervation. Herrick ('02) was concerned almost exclusively with 

 the sense of taste, in a narroAv sense, that is, the reactions to sapid 

 solutions through stimulation of the taste buds. He performed a few 

 experiments of a general chemical nature, insufficient, however, to per- 

 mit any conclusions. Almost the only work on vertebrates which 

 takes up the reactions of the nerves of general sensation to chemical 

 stimuli is that of Parker ('07, '08a, '08) on Amphioxus and Ameiu- 

 rus. His results will l)e reviewed later. 



Considering that a general chemical sense is proliably more primi- 

 tive in phylogeny than taste and smell and that a careful study of 

 such a general sense may do much to make clearer the development 

 of these two senses, as well as their physiology, it is strange that so 

 little has been done on this topic. This is especially true in the lower 

 vertebrates, where, in many cases, it is difficult to separate the re- 

 actions due to stimulation of the organs of taste and smell from those 

 due to the nerves of general sensation. 



COXDITIOXS oi' Exi'EKi:\rp:xTATiox. 



The substances used in this work were hydrochloric, nitric, and 



sulphuric acids for acid stimuli ; sodium, ammonium, and lithium 



chlorides for saline stimuli; sodium hydroxide for alkaline; cane 



sugar, dextrose, saccharine, and its carbonate for sweet; and quinine 



