DISCUSSION 723 



(I)) H\ ;i spcrial let liiii{|iu' A^iiilar aiul Siiks have succeeded in measuring 

 the iiun'imut tlireshoid ol normal human rods at all luminance levels iroui 

 dark adaptation to satiuatiou. iiul this lod luiulion is not likely to he 

 allecled hv cone inliihilion JKcause it iollows the simple VVeher-Fechner 

 relation until near saturation. Horeo\er. our rod nionochroniat without cone 

 iidiii)ition exhihits an identical relation and saturates at the same level. 

 And the ■'saluialion'" itsell is not an inhibition by cones, lor il has the 

 rhodopsin spectral sensitivity. Thus rods, not cones, catch the li,<>ht which 

 saturates. Does this answer your question? 



Dr. MacNiciioi.: Perfectly. 



