144 LLOYD M. BEIDLER 



of sugar response often declines with the duration of the experiment and 

 this decline always precedes that of the decline in the salt response. In 

 particularly long preparations, those over 20 hr, the response to NaCl 

 may decHne until the response to KCl is larger. What effect small changes 

 in the blood supply over long periods has on taste responses is not known. 

 The response does begin to decline within 15-20 min after the blood 

 supply is completely shut off to the tongue. The turnover rate of taste 

 cells should be affected by vitamin deficiencies, ionizing radiation, mitotic 

 inhibitors, hibernation, etc., which in turn should be reflected in changes 

 in taste responses. It is known from work in our laboratory that urethane, 

 an anaesthetic as well as a mitotic inhibitor, produces histological changes 

 in the taste bud within 40 hr after intraperitoneal injection. 



CONCLUSION 



The taste receptors are very sensitive and yet very rugged. They are 

 renewed continually and thus have a short life span. Their response to 

 chemical stimuli varies from one receptor to the next in the same population. 

 The response of the total population is very similar from one individual to 

 the next although large differences are noted from one species to the next. 

 It is not yet known with accuracy how much the response characteristics 

 of a particular single fiber depend upon the experimenter's disturbance 

 of the natural conditions of the taste system nor how they may change with 

 periods of time comparable to a sizeable fraction of the total life span of 

 the individual receptors. 



ACKNOWLEDGEMENTS 



The author's work was supported by a National Science Foundation 

 Grant No. G-14334, and an OflFice of Naval Research Contract No. 

 NONR-589 (00). 



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