OXYGEN AND LUMINESCENCE. 93 



and in B m/io Na 2 HPO 4 solution (P H : : 9) + Na 2 S 2 O 4 . The 

 tubes allow a flow of pure hydrogen through a lead tube to wash 

 out the air, and the only rubber parts are the stoppers of tubes 

 A and B. In such an apparatus the contents of A and B can 

 be mixed in hydrogen without the slightest blueing of leuco- 

 methylene blue and oxygen-free Cypridina luciferin can be 

 mixed with oxygen-free luciferase (by methods 3 or 4) without 

 any luminescence appearing. However, when the oxygen-free 

 Beroe extract (by methods 3 or 4) is mixed with the oxygen-free 

 m/io Na2HPO 4 solution, just as bright a luminescence occurs, as 

 in the control tests when mixed in presence of oxygen. 



The experiment has been varied by using Pt asbestos in the 

 Beroe extract and in the water and passing pure hydrogen through 

 the system for an hour (although methylene blue can be de- 

 colorized in two or three minutes by the same flow of hydrogen), 

 but a bright luminescence always results on mixing the Beroe 

 extract with the water in the hydrogen atmosphere. When air 

 is admitted and the fluid shaken, no further luminescence is to 

 be observed. 



The experiment has been repeated so often that I feel certain 

 that Beroe extract will luminesce in absence of dissolved oxygen . 

 Eucharis multicornis, another Ctenophore, behaves as Beroe, as 

 does also the medusa, Pelagia noctiluca. Pennatula phosphorea 

 extract, on the other hand, requires oxygen, as I had previously 

 observed for the pennatulid, Caver nularia haberi Harvey (1917). 

 A Pennatula extract in sea water mixed with fresh water in 

 absence of oxygen l gives no light but when shaken with air the 

 mixture luminesces faintly. It is somewhat surprising that the 

 pennatulids should differ in this respect from the Ctenophores 

 and Pelagia as the general aspects of the luminescence in these 

 forms is similar. 



None of these animals give the luciferin-luciferase reaction. 

 The luminescence seems to be connected with the dissolution of 

 granules. In the luminous slime of Pelagia, which sticks to the 

 finger when rubbed over the exumbrella, can be observed with 

 the microscope, cells densely crowded with granules somewhat 

 less than I n in diameter. These granules and some cell frag- 



1 Mixing in air of course results in luminescence. 



