ELECTROPHYSIOLOGICAL RESPONSES TO SUGARS 



79 



In the second series of experiments the following test-solutions were 

 used : 0.5 M sucrose, 0.5 m sodium chloride and a mixture containing 0.5 m 

 sucrose and 0.5 m sodium chloride. The concentration of the sodium 

 chloride solution was in one experiment reduced to 0.2 m, and the mixture 

 was adjusted accordingly. 



L-SOPBOSE SUCPOS£ 



Fig. L Structural formulas of sugars investigated. 



Altogether 43 functional single fibres from 25 dogs were studied, and the 

 integrated responses from the unsplit chorda tympani were recorded in all 

 of the experiments. 



RESULTS AND DISCUSSIONS 

 A. Responses to Sugars 



1. Responses of the whole chorda tympani. The integrated responses 

 obtained in one experiment are presented in Fig. 2. It appears that 

 D-fructose produced the largest response of all of the sugars as measured 

 by the deflection of the integrated beam from the base level. The other 

 ketohexose, L-sorbose, was roughly half as effective as a stimulus, d- 

 mannose was the most powerful stimulus of the aldohexoses. D-galactose 

 and D-glucose produced very nearly the same response in the experiment 

 shown in Fig. 2, but on the whole the latter proved to be the stronger of the 

 two. The 0.5 m solutions of the three disaccharides gave the following 

 order of decreasing stimulation ability : Sucrose>Maltose>Lactose, 

 sucrose being the second best stimulus of all of the sugars studied. 



We have used the recordings obtained with the integrator for a compari- 

 son of our results with the psychophysical data collected from investigations 



