JOHN BUCK 755 



that the phenomenon exists. Perhaps for the same reason biolumines- 

 cence seems to pose in exaggerated form the questions of origin and 

 evohition, questions which of course actually apply with equal force 

 to vision and indeed to all biology. Harvey (14) and Wald (30) 

 have touched briefly on biochemical aspects of this subject, but the 

 point that interests me particularly, the functional interrelations of 

 vision and photogeny at the levels of the organ and whole organism, 

 seems to have had little attention. One facet of the problem, however, 

 the question of whether bioluminescence can account for the well- 

 developed eyes of certain bathypelagic or abyssal forms, has been 

 termed by Welsh and Chase (31) ". . . one of the most baffling 

 problems associated with the biology of deep-sea animals." 



Photophore Anatomy 



Since the only direct indication of eye-photophore interrelation is 

 the alleged similarity in organ structure, it will be useful to look 

 at some of the details of the extensive literature. If we define "eye- 

 like" as involving an external-internal sequence of a window (cornea) , 

 lens (es) , photic tissue (in roughly the position of a retina) , reflec- 

 tor (tapetum) , pigment cup, and nerve, we find that organs more or 

 less meeting this requirement occur in some deep-sea fishes (13) but 

 reach their highest development in deep-sea squids and shrimps. The 

 figures^ illustrate the structures of a few examples, along with cor- 

 responding views of certain eyes. In addition to the minimal "eye- 

 like" structures it will be seen that the photogenic tissue is some- 

 times fronted by a striated "refractor" or "rod-mass," or the rod- 

 shaped individual photocytes themselves are packed into an oriented 

 layer reminiscent of the arthropod retina. No photophores have a 

 sphincter-type iris, though in some an aggiegation of chromatophores, 

 distal to the lens, simulates at least the function. 



Clearly, the term "eye-like" is a loose and subjective one, not per- 



* Since all the "evidence" is my interpretation of second-hand data, and since 

 we are primarily interested in comparing major details (similarity in minor de- 

 tails being neither required nor anticipated), and since, in any case, apparent 

 structural details vary with plane of section, fixation, staining technique, artistic 

 skill of observer, and other extraneous influences, it has seemed best to me to 

 summarize and simplify the individual pictures in semidiagrammatic fashion. I 

 have also taken the responsibility of assigning names to structures of uncertain or 

 disputed function. For example, light-generation in the Fig. 3 photophore has 

 been ascribed to both the reflector (26) and to the refractor (4) as well as to the 

 indicated tissue (7). My warm thanks are due Dr. Margaret Keister for executing 

 the diagrams. 



