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MORLEY R. KARE AND M . S. FICKEN 



and volume consumed. The rate at which the changing concentration of 

 the stimulus affects preference behavior appears to be a function specific 

 for each chemical. Further there is no predictable relationship between the 

 apparent hedonism and volume consumption. 



Leaving the realm of metabolism, let us consider response to the non- 

 nutritive saccharin. Figure 9 illustrates the range in response to this com- 

 pound. On the basis of this work one can suggest that pigs and rats over a 

 wide range of concentrations found it appealing while calves were in- 

 different. I might add that at a single concentration tested most chickens 

 found it slightly offensive and dogs markedly so. 



100 



80- 



50 



40 



CALVES 



PIGS 



RATS 



0.00025 00025 O025 025 



CONCENTRATION GMS/IOOML. 



SACCHARI N PREFERE NCES /WATER 

 OF CALVES, RATS. AND PIGS 



Fig. 9. A comparison of the response of calves, rats and pigs to saccharin 



solution. 



On this point T should qualify the remark " most animals ". We found 

 a minority of pigs that were offended (Kare, 1961) by saccharin at every 

 concentration offered. Similarly most dogs actively rejected saccharin in 

 low concentrations in their food, but a small minority tolerated if not 

 preferred it. 



This introduces the question of individual differences. Individual varia- 

 tion in taste ability (Ficken and Kare, 1960) was studied using 28 male and 

 28 female Barred Plymouth Rock-Rhode Island Red crosses, aged two 

 months. A single stimulus method was employed (modified from Duncan, 

 1960) and the test substances were ammonium, calcium and ferric chlorides 

 at three or four different concentrations. 



Different individuals had markedly different thresholds (the lowest 

 concentration at which the intake differed from that of water). For 



