ON OFF 



muiua 



10 mv. 



iiiuiiiinu 



20 msec. 



iUiuliXL 



mm 



Fig. 14 (A) 



i^nuuuuiuuuilUU>^UJ.>UL-LX-l- 



FiG. 14 (B) 



Fig. 14. (A) Intracellular records from a photosensitive neuron in the 

 sixth abdominal ganglion of the crayfish. In all frames, the lower trace 

 indicates the resting level of internal potential. Light (middle column) 

 evokes a depolarizing receptor potential, and the latter generates impulses.*' 

 (B) Response to light of a primary photosensory neuron in the eye of a 

 nudibranch mollusc. A large depolarizing receptor potential generates 

 impulses which, from their small size, apparently are not invading the 

 recording site. The calibration markers indicate 50 millivolts and 

 500 milliseconds. The lower trace is elevated during the light stimulus. 

 (A from Kennedy and Preston,®^ Fig. 7; B from Barth.^" Fig. zA.) 



37 



