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LIGHT AND LIFE 



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INHIBITION 



OFF 



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~ x, 



A 



• — • 



ON /' 



500 600 700 



WAVELENGTH IN MILLIMICRONS 



\ 



I 



Fig. 10. Intensity necessary to elicit various types of threshold responses from 

 a single ganglion cell at different wavelengths. Experimental conditions, scales, 

 and symbols as in Fig 7. Thresholds for inhibition of discharge during illumina- 

 tion plotted as triangles. 



400 500 



WAVELENGTH IN 



600 700 



MILLIMICRONS 



Fig. 11. Intensity necessary to elicit various types of threshold responses from 

 a single ganglion cell at different wavelengths. Stimuli 0.5 sec in duration were 

 repeated at 2-sec intervals. Intensity plotted on a log quantum scale. log 

 units = 2.6 X 10" quanta/sec/cm- for all wavelengths. NOIF: Dining the 30 

 minutes necessary to determine the 3 sets of each curve the "off" components 

 changed slightly or not at all, while the "on" component became progressively 

 more sensitive with little change in shape, a result confuming earlier evidence of 

 a degree of independence of the two processes. 



