266 



C. PFAFFMANN 



2 days it selected water. On every one of the 10 days post dialysis, the 

 animal preferred NaCl and ingested large quantities of it. It is of interest 

 that the preference for salt was still apparent on the tenth day, long after 

 the major disequilibrium in Na metabolism had presumably been corrected. 

 This animal continued to show an enhanced salt preference for 34 days after 

 dialysis. This points to the importance of a single need-reducing experi- 

 ence in enhancing the preference value of a taste stimulus. 



The selectivity of the preference for NaCl is shown in Fig. 7, where 0.1 

 NaCl was paired with 0.1 KCl. Note the greatly enhanced intake and pre- 

 ference for NaCl after dialysis and the decreasing intake of KCl in successive 



D-t2 



PRE-DIALYSIS 



LAST SESSION 



POST-DIALYSIS 



FIRST SESSION 



\' DIM NoCI I MIN. 



Fig. 7. Record of preference behavior for NaCl over KCl after dialysis. 



1-min periods which resembles an extinction series as the animal comes to 

 make a clearer discrimination between the two salts. 



Further data on the question of specificity for taste of different salts 

 and on the effect of post-ingestion factors is provided by a recent study 

 Dr. Nachman just completed while a guest investigator in our laboratory. 

 Nachman (1962a), using his 10-min two-bottle test, with pre-training to 

 insure sampling from both tubes, observed that naive adrenalectomized 

 rats showed an equal preference for NaCl and LiCl. In the same test, 

 sodium solution was readily preferred to K, NHj, or Ca solutions. On 

 the other hand, Fregley (1958) reported that rats avoid LiCl solutions in 

 the 24-hr test. Lithium salts have been shown to be toxic to a variety of 

 animals. In dogs, the major symptoms were a marked diuresis, tremor, 



