ELECTROPHYSIOLOGICAL RESPONSES TO SUGARS 



187 



with stronger stimulating power and sweeter taste. This certainly does not 

 imply that sweetening power is a simple function of the water solubility ; 

 but that the molecular characteristics responsible for water solubility also 

 are important for the events which lead to stimulation of the proper recep- 

 tors can hardly be circumvented. It has been hypothesized that sweetening 

 power is often associated with low water solubility (Crozier, 1934, quoted 

 by Pfaffmann, 1959), but in the case of the sugars this does not seem to be 

 true. 



B. The Peripheral Interaction between Salt and Sugar 



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

 the whole chorda tympani to 0.5 m solutions of sucrose and sodium chloride, 

 and to a mixture containing 0.5 m sucrose and 0.5 m sodium chloride are 

 shown in Fig. 9. There was no water rinse between two successive applica- 



Sucrose 



aa 



Sucrose 



Sucrose 



Mixture 



Fig. 9. Integrated responses recorded from the whole chorda tympani nerve. 



Note the depressing effect of sodium chloride on the response of the mixture 



in D. Time in seconds. 



tions of the test-solutions. Figure 9 A, B and C are the control experi- 

 ments in which the same solution was applied twice in succession. As seen, 

 there was in no case a response to the second application. Figure 9 D shows 

 that the mixture when applied after 0.5 m NaCl did not elicit any response, 



