124 THE PHYSIOLOGY OF INSECT SENSES 



attractant (Bombyx mori) hexadeca-diene-(10, 12)-ol-(l) (Butenandt, 

 Bechmann, Stamm, and Hecker, 1959), electrical activity increases in 

 the male antenna but not in that of the female. When cyclohexanon or 

 sorbinol are employed as stimuli activity increases in both sexes. The 

 spikes are superimposed on a complex slow potential which Schneider 

 (1957 a) has termed the electroantennogram (EAG). The amplitude 



-70 — 



-60 



:2 



o 



^ -50 



-40 



-30 



-20'^ 



Fig. 75. Plot of the logarithm of the olfactory rejection concentration for 

 blowflies against the adsorption constant at an oil/air interface 

 (logio Kojd). The broken line represents the slope expected if Ijp were 

 to increase regularly with chain length. Threshold data from Dethier 

 and Yost (1952). (Redrawn from Da vies and Taylor, 1959.) 



depends upon the concentration of the odour, and the wave form, on 

 the kind of molecule. Many compounds in high concentration elicit 

 an EAG (ether, ethanol, propanol, butanol, xylene, etc.), but at 

 extreme dilution only the natural sex attractant elicits an EAG. Its 

 wave form is characteristically different (Schneider, 1961). There are 

 no significant differences in the normal EAGs of a male antenna 

 when the stimuli employed are the glands of related saturniid species, 



