154 THE NATURE OF ANIMAL LIGHT 



light, but always with negative results. Likewise my 

 attempts to obtain light during the electrolysis of salt solu- 

 tions containing pyrogallol by means of the nascent oxy- 

 gen at various kinds of anodes have met with negative 

 results. A similar case is presented by luciferin which 

 oxidizes spontaneously (most rapidly in presence of 

 alkali) without light production and only produces light 

 when oxidized in presence of lucif erase. 



To sum up the results of the dynamics of chemilumi- 

 nescence we may say that certain oxyluminescences occur 

 only if the substance is oxidized in a particular way under 

 definite conditions of temperature and concentration and 

 that this is probably due to a favoring of one step (with 

 which the luminescence is associated) in a chain of oxi- 

 dations. Providing temperature and concentration are 

 such as to favor the step responsible for luminescence, then 

 higher temperature and greater concentration result in 

 increased intensity of luminescence. 



Let us now turn to luminous organisms and consider 

 the effect of temperature and of concentration of reacting 

 substances (oxygen, luciferin and lucif erase) on the lumi- 

 nescence. We have already seen that luminescence of a 

 lucif erin-lucif erase mixture begins with an extraordinarily 

 low oxygen tension and increases in intensity with in- 

 creasing tension of oxygen, but that very soon an oxygen 

 tension is reached where a maximum luminescence is ob- 

 tained and further increase of oxygen tension gives no 

 brighter light. In this respect the luminescence intensity 

 — oxygen tension curve is no doubt very similar to the 

 haemoglobin saturation — oxygen tension curve. Hasmo- 

 globin is about 50 per cent, saturated at 10 mm. oxygen 

 pressure, 80 per cent, saturated at 20 mm. oxygen pressure 



