260 



C. PFAFFMANN 



the magnitude of deflection as recorded with summator and inkwriter was 

 expressed as a ratio of the response to 0.01 m NaCl. In many preparations, 

 however, the same absolute level of response was obtained. When higher 

 ampHfication was required, this could be attributed to incidental features 

 such as trauma to the nerve, variation in inter-electrode spacing, variations 

 in moisture, and shunting of the electrodes, etc. 



No systematic differences between experimentals and controls were 

 observed either in absolute or relative magnitudes of response to the supra- 

 threshold stimuli, NaCl, NaAc, KCl, NH4CI, CaCU, all at 0.1 m, or 0.1 m 

 quinine, 1.0 m sucrose, or 0.003 m HCl. Figure 2 compares the responses 

 to a series of NaCl concentrations. These functions are the same for both 



4.0 



CO 



z 



O 3.0 



Q. 



CO 



2.0 



1.0 



-1.0 



A A CONTROL 



• • EXPERIMENTAL 



A-4' 



1.0 



-05 



np -3.5 -3 25 -30 -275 "25 -2.0 -l 5 



LOG MOLAR NaCl 



Fig. 2. The magnitude of chorda tympani responses to NaCl solutions in normal 

 and NaCl-deprived rats. 



experimentals and controls and are very similar to those reported for the 

 rat earlier by Beidler (1953) and by Pfaff'mann (1955). In our previous 

 accounts, we used one-minute intervals of stimulation and 1-min intervals 

 between stimuli ; here we used 3-min intervals, which show more clearly 

 the decrement in resting activity upon the application of HoO or weak 

 saline solutions (see Fig. 3). Zotterman (1956) made similar observations 

 in his studies of the water receptor in diff'erent species. The rat does not 

 give a water response except as an off'-type discharge following sucrose or 

 HCl stimulation. In other species, the water response is influenced by 



