Sheldon, Reactions to Chemical Stimuli. 275 



iiGction only the taste buds and associated nerves. Other authors have 

 argued that, in addition to these structures, the nerves of general 

 sensation take part in the sense of taste in man. Such a view is sup- 

 ported by the work of Caraerer ("70), von Vintschgau ('79b), von 

 Anrep ('80), Adducco and Mosso ('86), Hooper ('87), Berthold 

 ('88), Oehrwall ('91), Shore ('92), Kiesow ('94a), Vinci ('97, '99), 

 Fontane ('02), Ferrari ('04) and Herlitzka ('07). 



Extensive work has also been done on the sense of smell in man 

 from the physiological, and to a less extent the chemical viewpoint, 

 as may be seen by consulting bibliographies such as that given by 

 Zwaardemaker ('95) and Bawden ('01). There will be no general 

 consideration of the subject here, as it does not bear directly on the 

 problem at hand. It is to be noted, however, that in connection with 

 the olfactory organ as well as the gustatory, the free nerve endings 

 take part in the reactions secured. Physiological evidence is noted 

 by Haycraft ('00b), while the presence of such terminations has been 

 demonstrated by a number of writers from Grassi and Castronovo in 

 1889 to Eead (1908). 



In spite of the evidence presented by these authors, outside the 

 single work of Grlitzner ('94), little has been done on mammals to- 

 ward a study of the reactions of the free nerve termini gener- 

 ally to chemical stimuli. This has been due partly to precon- 

 ceived ideas on chemical sense and partly to the feeling that nothing 

 is to be gained by a general study of the chemical sense among the 

 vertebrates, — even to the extent of including smell and taste under 

 the same category. Such is the view of Zwaardemaker, who says 

 ('03), "Bei den Wirbelthieren jedoch sind Geruchs- und Ge- 

 schmackssinn in vieler Hinsicht so grundverschieden, dass es meines 

 Erachtens keine Empfehlung verdient, sie zusammen zu behandeln." 



On the chemical senses of the lower vertebrates little has been done. 

 Bateson ('90a, '90b) discussed the senses of smell, taste, and touch 

 in several fishes. The work is of little value in the present 

 connection. In 1894 Kagel published his great monograph on smell 

 and taste. Nagel repeatedly uses the term chemical sense, always 

 meaning, however, the combined organs of taste and smell and not a 

 general chemical sense. He stimulated selachians, teleosts, and am- 



