THE VISUAL PIGMENTS 



Again, from wald and brown's value for the molecular extinction 

 coefficient of visual purple, viz. 40,600 cm^ per mole equivalent of 

 retinene (p. 83) it follows that such a solution would contain 

 2-5 X 10~® moles of retinene. In other words, the molar concentra- 

 tion of RD-1 and retinene are equal. From this hubbard concluded 

 *RD-1 contains one molecule of rhodopsin, with a molecular weight 

 of about 40,000, and carrying a single chromophore composed of 

 one molecule of retinene.' 



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94 



