CHEMORECEPTOR MECHANISMS 



15 



B 



i.O/ji 



0.5p 



Fig. 14. Electron micrograph of labellar chemoreceptor of the blowfly, Phormia 

 regina (through the courtesy of E. Kafig, Naval Medical Research Institute, and 

 M. Wolbarsht, The Johns Hopkins University). 



^^^p^, 



■ — — »■■ m , . ■ ., 



ik i ii ii tori , < l i i . i^ .i t^ . ft i i^,4ate i^ 



^t^f^^^^^^M^^ 



.. . .. 



J,,,; 



Fig. 15. Activity recorded from tip of a single labellar hair during chemical stimu- 

 lation. Large spikes, 0.5 mV. Time marks, 0.01 sec. Upper record: stimulation with a 

 mixture of 0.12 M sucrose and 0.154 M NaCl. Note paired spikes. Lower record: 

 stimulation with 0.154 M NaCl. 



insects we know that very similar, if not identical, relationships can be demon- 

 strated. These relationships strongly suggest that there is a highly selective 

 receptor substance or site with which the sugar must react. The fact that re- 

 sponse ceases almost immediately upon removal of the applied stimulating so- 

 lution suggests that the sugar is rapidly removed from the receptor site. It can 



