SPECULATIONS ON THE INTERRELATIONS AND 

 EVOLUTION OF PHOTIC ORGANS 



John Buck 



Laboratory of Physical Biology 



National Institute of Arthritis and Metabolic Diseases 



National Institutes of Health 



Bethesda, Maryland 



Introduction 



BioiDhysicists and biochemists are probably not fully conscious of 

 the activating effects of their emanations upon old-fashioned zoologists, 

 even though these effects sometimes take rather bizarre forms. At 

 the 1954 symposium on our present subject (18), for example, I 

 remember one bemused individual, carried away by the parallels be- 

 tween the role of adenosine triphosphate (ATP) in fireflies and in 

 muscle, asking whether muscles give off light during relaxation. In 

 my case, overexposure to erudition has triggered a large release of 

 speculative energy channeled toward possible evolutionary relations 

 of photogeny to vision, a subject offering splendid opportunities for 

 the exercise of free association. The direction of speculation could 

 perhaps have been justified by the precedent set by various other con- 

 tributors at more sophisticated levels, or still more strongly by the 

 reciprocities implicit and explicit in our Symposium title and pro- 

 gram, but in point of fact two further stimuli helped orient my 

 thoughts. One was the existence of reports, which I had never taken 

 time to follow up in detail, indicating that there is a provocative 

 structural similarity between certain eyes and certain photophores. 

 The other was the remark of a colleague, upon viewing the first record 

 of action potentials in a photophore nerve (3) , to the effect that "If 

 you read that backwards it could be an electroretinogram." This 

 latter item really indicates no more than that a photophore, like an 

 eye, may have a nerve supply, but does serve to emphasize the lack 

 of the sort of physiological information which might permit a com- 

 parison of photophore excitation with optic nerve excitation. 



Dr. Arnold has already drawn the conclusion that demonstrations 

 of ])ioluminescence are necessary because no one can really believe 



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