BIOLOGY OF LIGHT PRODUCTION MALUF 397 



In a classical work, Langley and Very (1890), by comparing the 

 spectrum of the firefly, Pyrophorus noctilucus, with a solar spectrum 

 of equal intensity, showed that the brevity in extent of the luminescent 

 spectrum is not due to weakness of the red and blue rays but to their 

 absence (limits: \=4680 A. to X=0.640 A.). 



In the firefly and in ostracods, at least, a rise in temperature shifts 

 the spectrum toward the longer wave lengths, i. e., toward the red 

 (Macaire, 1821 ; Polimanti, 1911 ; Harvey, 1924, 1927b). This condition 

 is true both in vivo and in vitro. Harvey (1927b) has suggested that 

 this may be due to a change in the aggregation state of the colloidal 

 particles of the luciferin. 



SUMMARY 



1 . A luminescent body is one which radiates light at a low tempera- 

 ture and the light of which is not the result of (high) temperature. 



2. Bioluminescence is a form of chemiluminescence and, except 

 for certain primitive Metazoa, requires free oxygen. 



3. Among arthropods, light-producing organs occur in various 

 crustaceans, centipedes, and insects. 



4. Unlike centipedes, luminescence in beetles serves for sexual 

 attraction. 



5. Bioluminescence is controlled by the oxygen supply to the 

 luminescent cells. As a result of nervous stimuli (which are often 

 periodical), the metabolic rate of the photogenic cells is presumably 

 raised with the consequent liberation of metabolites. The latter, by 

 raising the osmotic pressure of the tissue fluids, as evidence indicates, 

 presumably would cause a withdrawal of fluid from the tracheoles of 

 the photogenic cells and would, thus, supply the cells with more 

 oxygen. 



6. There are several luciferins and lucif erases. The latter group 

 not only catalyze the oxidation of luciferin but evidently become 

 activated by the process and thus emit light in reverting to the original 

 state. 



7. Under conditions which simulate the biological, the oxidation of 

 luciferin will not produce light except when reacting with lucif erase. 



8. The total efficiency of bioluminescence is apparently very low, 

 being of the magnitude of approximately 1 percent. The radiational 

 efficiency of bioluminescence may prove to be the highest that is 

 known to science. 



9. All light waves emitted are well within the range of the human- 

 visible spectrum (X=0.390 to 0.810/x). The luciferase and not the 

 luciferin determines the type of spectrum in bioluminescence. 



The writer is much indebted to Prof. E. Newton Harvey (Princeton 

 University) and Dr. John B. Buck (Carnegie Institution) for having 

 read and criticized the above article before its final printing. Needless 

 to say, however, all responsibility falls on the author. 



