96 DIETRICH SCHNEIDER 



On the other hand, the variabihty may also derive from specific physio- 

 logical conditions due to the location of the recording electrode. We still 

 do not know whether only a rather small group of olfactory nerve cells near 



Fig. 8. Three-dimensional models of the four geometrical isomers of hexa- 



decadienol. From above to below : 10-/ra/7.y, 12-c/.v ; lO-cis, l2-trans ; 10-m, 



12-C/.S- ; \2-tram, \2-trans. C-atoms are black ; H-atoms are white ; O-atoms 



are grey (courtesy of Dr. E. Hecker). 



the electrode tip is mainly responsible for the EAG. If this is the case, 

 response fluctuations, sensitivity shifts, and even the higher sensitivity to 

 an isomer could be explained by physiological differences of the receptor 

 cells from which the electrode is recording. The number of cells cannot 

 be too small, however, since we usually record with electrodes so wide that 



