TEMPERATURE CHANGE ON THE RESPONSE OF TASTE RECEPTORS 163 



COMPARISON OF THE RESULTS ON CATS WITH THOSE ON 

 HUMAN SUBJECTS AND ON FROGS 



Our results shown above are not consistent with the work by Hahan 

 (1936), but are in rather good agreement with the classical v/ork by Weber 

 (1847). Recently Shimizu, Yanase and Higasihira (1959) investigated the 

 relationship between taste sensitivity of 27 Japanese girls aged 20-22 years 

 old and temperature of taste solutions. Their results are summarized in 

 Fig. 13. Most of the subjects showed the maximal sensitivity to NaCl and 

 sucrose at the temperature of 30-40 C, and nearly half of the subjects 

 showed the maximal sensitivity to quinine and tartaric acid at about 35'C 

 although the remaining half showed declining sensitivity to quinine and 

 tartaric acid with increasing temperature of solutions. Therefore our 

 results on cats are in good agreement with those on human taste sensations 

 by Weber and by Yanase et al., although the optimal temperature in cats 

 is about 30 C while that in human taste sensation is higher than 30 C. The 

 difference is possibly attributed to higher temperature in the human tongue 

 than that in the tongue of anaesthetized cats. 



15 



20 



25 



50 



55 



30 35 40 45 



Solut ion temperature (°C ) 



Fig. 13. Relationship between taste sensitivity of human subjects and tempera- 

 ture of taste solutions. The curves are drawn schematically from results on 

 27 Japanese girls. From Shimizu, Yanase and Higasihira, 1959. 



Kimura (unpublished), recording impulse discharges in single nerve 

 fibres in the glossopharyngeal nerve of frogs, and Yamashita (unpublished), 

 recording the integrated response of the whole glossopharyngeal nerve, 

 investigated the relationship between magnitude of the neural response and 

 temperature of taste solutions. Results by Yamashita show that therfe is 

 no optimal temperature for taste sensitivity in frogs. In Fig. 14 is showh 

 an example of the response of the glossopharyngeal nerve to stimulation 



