, ; E. NEWTON HARVEY. 



ments will pass filter paper and centrifuging such a filtrate will 

 throw down the cell fragments and many granules, leaving 

 suspended only granules. When added to fresh water this 

 centrifuged material gives a bright luminescence (because many 

 granules are thrown down) while the suspension above gives a 

 fainter luminescence. I could observe no cells in the suspension 

 but when mixed with fresh water in complete absence of dis- 

 solved oxygen (method No. 4, hydrogen passed 20 mm.), as 

 bright a luminescence occurred as when oxygen was present. 

 I therefore believe that the oxygen is bound in these photogenic 

 granules and that luminescence occurs upon their dissolution. 

 That just enough or more than enough oxygen is so bound would 

 be indicated by the fact that opening the tube containing the 

 mixed fluids to the air results in no further luminescence. 



This same experiment has been repeated with filtered and 

 centrifuged Beroe extract, with the same result, luminescence of 

 granular material in absence of oxygen. 



The Radiolaria also require no free oxygen for luminescerice. 

 Thalassicolla mideata and also colonies of Colozoun inerme 

 mixed with platinized asbestos in sea water through which pure 

 hydrogen is passed for 45 minutes will still luminesce whenever 

 shaken. A colony of Colozoun inerme was broken up into 

 separate cells (but these left uninjured) mixed with platinized 

 asbestos and pure hydrogen passed through it for 20 minutes. 

 It was then mixed in a pure hydrogen atmosphere with water 

 and platinized asbestos through which pure hydrogen was passed 

 for 20 minutes. A bright "starry' luminescence resulted, 

 similar to that of Beroe extract when mixed with water. 



After these rather startling (to me) results I thought it worth 

 while to reinvestigate the necessity of oxygen for luminescence in 

 other animals, noting carefully if the lack of oxygen caused lumi- 

 nescence to disappear when the whole animal was tested and 

 when its secretion was tested. For we are especially interested in 

 knowing whether the luminescence of dissolved- or finely divided 

 photogenic material is stopped by lack of oxygen rather than 

 whether intact cells cease to luminesce in absence of oxygen. 

 It is of course perfectly well known that luminous bacteria cease 

 to luminesce in absence of oxygen but one could not make the 



