JOHN BUCK 331 



mediate"). The Snell hypothesis is subject to the objections inherent 

 in any hypothesis of control by oxygen hmitation. The hypothesis that 

 formation of active intermediate is rate-hmiting in normal control has 

 the attractive feature that the rate could be affected either by oxygen 

 limitation ( the hypoxic glow-pseudoflash phenomenon ) or, in normally 

 oxygenated animals, by making some other reactant limiting such as 

 acetate, as proposed in Dr. McElroy's nerve-action control suggestion. 

 There is, however, a possible obstacle in that I have not been able to 

 demonstrate a relation between length of hypoxia and magnitude of 

 pseudoflash. Possibly this obstacle can be resolved with additional 

 work. 



The end-cell control hypothesis, though seriously defective in some 

 respects, has in it the germ of a possibly important concept. As I 

 pointed out in 1948, the mechanism which controls the hypoxic glow- 

 pseudoflash phenomenon ought to be one which requires energy 

 expenditure, that is, the animal has to do work to keep itself dark. 

 This would accord well both with the effects of hypoxia and with the 

 fact that fireflies develop a long-lasting glow during anesthesia and 

 after death. Such an "active dark" mechanism need not be and ought 

 not to be restricted to oxygen limitation. Although it is perhaps pre- 

 mature to propose specific neuroeffector or chemical control mecha- 

 nisms in either fireflies or other organisms, there is at least the 

 suggestive analogy of skeletal muscle, in which work is done to main- 

 tain the tissue normally in the relaxed state, and the well-established 

 presence, in some Arthropods, of inhibitory nerves. 



Refere nces 



Alexander, R. E. 1943. Factors controlling firefly luminescence. /. Cellular 

 and Comp. Physiol, 22, 51-71. 



Brown, D. E. S., and C. V. King. 1931. The nature of the photogenic re- 

 sponse of Photiiris pennsylvanica. Physiol. Zool., 4, 287-93. 



Briicke, E. 1881. Vorlestingen iiber Physiologie. 3rd ed., 1, 59-61. 



Buck, J. B. 1948. The anatomy and physiology of the light organ in firefles. 

 Ann. N. Y. Acad. Sci., 49, 397-482. 



Buck, J. 1953. Bioluminescence in the study of invertebrate nervous sys- 

 tems. Anat. Record, 117, 594. 



