V. G. DETHIER 



■3.0 



-4.0 



REJECTION THRESHOLDS 

 OF PHORMIA 



DIFFERENCE THRESHOLDS OF 



MAN (FROM DATA OF RENOVIST) 



0.4 



0.8 



LOG NUMBER OF C ATOMS 



Fig. 3. Comparison of relative effectiveness of homologous alcohols in stimulating 

 tongue of man and tarsal receptors of the blowfly (Dethier, 1951b). 



all but a very few cases the information was derived from stimulation of popula- 

 tions of mixed receptors, and to what degree the information can be extrapo- 

 lated to single receptors remains to be seen. Until very recently the situation in 

 insects was the same. A great deal of information had been amassed as a result 

 of stimulating receptor fields. Just as the criteria with mammals were subjective 

 or behavioral, so in insects they were behavioral. In general the picture which 

 emerged was one of two taste modalities, acceptable and unacceptable. (Some 

 experiments in progress now suggest that this conclusion may be an over-simpli- 

 fication.) Stimulation of insect receptors by electrolytes (Frings, 1946, 1948; 

 Frings and O'Neal, 1946; Hodgson, 1951) revealed that, with minor exceptions, 

 the stimulating efficiencies of cations and anions follow the pattern already 

 given. Furthermore, there was evidence that both ionic species are contributing 

 to the event. The similarity of acid stimulation in insects to that in man has 

 already been mentioned. In the case of sugars the high degree of molecular spe- 

 cificity already noted with man is found to exist in insects in as high or possibly 

 in a higher degree (von Frisch, 1935; Hassett, Dethier, and Cans, 1950; Dethier, 

 1955). Data relative to the stimulating effects of organic compounds are far 

 more complete for insects than for man (Dethier, 1953). Here also there is a 



