178 H. T. ANDERSEN, M . FUNAKOSHI AND Y. ZOTTERMAN 



problem and a relatively modest aim, namely, study to the stimulating 

 ability of a series of intimately related substances and, if possible, to cor- 

 relate this parameter with at least one physico-chemical property of the 

 compounds used. For this purpose we selected three stereo-isomeric aldo- 

 hexoses D-galactose, D-glucose and D-mannose, two ketohexoses D-fructose 

 and L-sorbose ; and in addition three disaccharides, namely, sucrose, 

 maltose and lactose were tested. 



During the investigation we became interested in the interaction of gusta- 

 tory stimuli on the peripheral level, and carried out a second series of 

 experiments in order to study this phenomenon with respect to salt and 

 sugar. This paper accordingly falls in two parts dealing with sweet stimu- 

 lation, and the peripheral interaction between sweet and salty stimuli, 

 respectively. 



METHODS 



Mongrel dogs were used in the experiments. Because all of the four 

 classical taste qualities, as well as the water taste, are mediated through the 

 chorda tympani in the dog (Appelberg, 1958), only fibres running in this 

 structure were studied. 



Detailed information about the experimental procedure has been fur- 

 nished in a series of previous publications and will not be repeated here 

 (Zotterman, 1936 ; Liljestrand and Zotterman, 1956 ; Kitchell et ah, 

 1958 ; Gordon et al, 1959 ; Konishi and Zotterman, 1961). 



The receptors of the tongue were stimulated with 0.5 M solutions of the 

 monosaccharides D-galactose, D-glucose, D-mannose, D-fructose and L- 

 sorbose, and the three disaccharides sucrose, maltose and lactose, which 

 are a-D-glucopyranosyl-/i-D-fructofuranoside, a-D-glucopyranosyl-D-glu- 

 copyranose and /?-D-galactopyranosyl-D-glucopyranose, respectively 

 (Fig. 1). 



Fresh samples of the solutions were made up 2-3 hr before use, so that 

 fermentation was negligible, whereas mutarotation would reach equili- 

 brium. Throughout the experimental period the solutions were kept in a 

 water bath which was maintained at 35-36°C. The temperature receptors, 

 therefore, remained silent when the sapid solutions were applied to the 

 tongue. Similarly, precautions were taken as to the arrangement of the 

 dispensing apparatus, so that no nervous discharge from the mechano- 

 receptors was elicited when the test-solutions were poured on to the sur- 

 face of the tongue. 



For the purpose of the present investigation the specificity of the pre- 

 parations studied was tested with water, 0.5 m NaCl and 0.01 m quinine in 

 addition to the sugar solutions. 



