200 H. DIAMANT AND OTHERS 



It is interesting to note that the alcohol even at as low concentration as 

 0.2 M obviously depressed the positive response to water. The immediate 

 depressive effect of alcohol is still more marked at 2 m and 3 m concentrations 

 before the slow onset of the positive response (Fig. 8). The response to the 

 subsequent application of water was only slightly stronger after higher 

 alcohol concentration than after the weaker solutions. 



In order to obtain more detailed data, the chorda tympani of the dog was 

 split into fine strands. We thus obtained one preparation which responded 



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0. 5M NaCl 



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0. 02M Quinine 



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7M Ethanol 



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Fig. 9. Records from a fine strand of the dog's chorda tympani. Note the 

 responses to acid and quinine and the weak response to sucrose and alcohol. 



Time in seconds. 



to acid and quinine but only weakly to sucrose and not to salt (Fig. 9), and 

 another preparation which showed a massive response to sucrose but not to 

 acid, salt or quinine (Fig. 10). The response to alcohol was positive in 

 both cases after a 4 to 6 sec latency. It was, however, much more pro- 

 nounced in the strand containing fibres strongly responding to sucrose. 



A similar series of alcohol tests were made on 13 subjects who reported 

 the taste of alcohol solutions poured on their tongue. The reports were 

 very varied. As will be seen from the diagram of Fig. 11 the gustatory 

 threshold varied but the median value was 0.5 m. This was thus the thres- 

 hold concentration of alcohol at which they felt a definite taste. This taste 

 sensation varied between sweet, sour and bitter. None reported salt except 

 at much higher concentrations. Seven subjects reported sweet taste while 

 the remaining six experienced no sweet sensation at any concentration. 

 Bitter taste was reported by all 13 subjects at a threshold median value of 

 0.8 M. Sour taste was reported by six subjects at various concentrations. 

 Only three subjects reported a salty taste with thresholds 0.7, 2 and 3 m 

 respectively. All subjects but one felt a smarting or burning sensation at 

 concentrations above 3 m. 



