LmkhI W ii k ii i lff ii i« ii i«i nr r ■!»» T lt an iit P i iiflffimmifm 



Fig. 8.20. Retinal Action Potentials; (a) Octopus (Eledone moschata). 

 (b) Eye-spot of Starfish (Asterias) 



Upward deflexion indicates negativity of lead towards external ends of sensory cells. 

 Time scale, all records, i sec. Duration of exposure shown below retinal potentials. In- 

 terruption of upper starfish record was 3 sec. ((a) from Frohlich, 1921 ; (b) from 

 Hartline et al. (63).) 



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Fig. 8.21. Electrical Responses of the Lateral Eye of Limulus 

 Action potentials of an isolated ommatidium and its nerve strand, in response to 

 short flashes of light (20 msec) at three intensities (relative values, top to bottom, 

 1-0, 0-1, 001). Upper trace, retinal action potential; lower trace, spike potentials. Flash 

 indicated by black bar above time trace near beginning of each record. Time scale, 

 0-2 sec. (From Hartline et al. (63).) 



