388 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



tion of light by Cypridina hilgendorfii is not the result of oxidation. 

 Four years prior to Kanda's work, Harvey's (1916a) experiments, in 

 which oxygen was replaced by hydrogen, showed that oxygen is neces- 

 sary for light production in Cypridina hilgendorfii. Harvey, then, 

 also called attention to the fact that every other organism studied was 

 found to require oxygen for luminescence. In reply to Harvey's 

 criticism, Kanda endeavored to justify his previous results by checking 

 his technique on a Japanese firefly, Luciola vitticollis. In this animal 

 no light was produced by the isolated photogenic organs in an atmos- 

 phere of pure hydrogen or nitrogen, or in a vacuum. The intensity of 

 light was greatest in an atmosphere of pure oxygen. Kanda thus 

 concluded that his technique was quite irreproachable and that the 

 production of light by L. vitticollis is the result of oxidation while that 

 in Cypridina is not. Biologists were now faced by a new enigma — why 

 Cypridina can luminesce without oxygen while this phenomenon in 

 Luciola imperatively requires oxygen. That this problem was only 

 man-made soon became apparent when Harvey (1920) removed all 

 traces of the oxygen present in commercial hydrogen gas by passing 

 the commercial product over hot platinum coils. Under such condi- 

 tions the oxygen, present as an impurity, combines with an equivalent 

 amount of hydrogen and forms water. When gaseous hydrogen so 

 treated was used, all light production by C. hilgendorfii completely 

 disappeared. "The luminescent secretion of Cypridina hilgendorfii 

 will still give off much light if hydrogen containing only 0.4 percent 

 oxygen is bubbled through it . . . At 7 mm of oxygen [i. e., 1 vol. 

 percent] the light of Cypridina is as bright as if the solution were satu- 

 rated with air [152 mm of oxygen]" (Harvey, 1919). In 1923, Harvey 

 and Morrison described a method for measuring the concentration of 

 oxygen necessary to allow just perceptible luminescence of luminous 

 bacteria. The value was 1 part by weight of oxygen to 37 X 10 8 cc of 

 sea water. Shapiro (1934) studied the light intensity of luminous 

 bacteria as a function of oxygen pressure. 



More recently the question as to whether free oxygen is necessary for 

 luminescence of the luciferin-lucif erase extracts of all luminous animals 

 became reopened (although unfortunately not to any great extent) 

 when Harvey (1926b) and Harvey and Korr (1938), even by the use of 

 the most drastic methods, found that a few animals (or dried extracts 

 of the same) can luminesce without oxygen. These are the Cteno- 

 phora, the medusa Pelagia noctiluca, and radiolarians. All luminous 

 pennatulids, annelids, echinoderms, arthropods, and cephalopods 

 could not luminesce without atmospheric oxygen. Harvey suggested 

 that, in the former, the oxygen may be bound up by the photogenic 

 granules. It is possible, on the other hand, especially since "stored 

 oxygen" has gained disfavor, that these lower Metazoa are still 



