142 PHOTOGENIC REACTION IN CYPRIDINA 



As almost all animal tissues contain reductases, it is not surprising 

 to find that a freshly prepared and filtered extract of Cypridina con- 

 taining oxyluciferin and luciferase which gives no Hght on shaking, 

 will, on standing in a stoppered tube for 24 hours at room tempera- 

 ture, give light when air is admitted.^' While this may be due to 

 the development of bacteria with a reducing action it does not seem 

 likely, as under the same conditions methylene blue is not reduced 

 in 24 hours and there is no turbidity or smell of decomposition in the 

 tube. In 48 hours bacteria do appear and methylene blue is also 

 reduced. If we add chloroform, toluene, or thymol to the tubes of 

 Cypridina extract to prevent the growth of bacteria, and allow them 

 to stand 48 hours, upon admitting air the tube with chloroform gives 

 no Hght but the tubes with toluene and thymol do give Kght although 

 it is not so bright as if they were absent. I beheve that these sub- 

 stances have a destructive action on the reductases, most complete in 

 the case of chloroform. 



I have not been able to demonstrate that a Cypridina extract will 

 reduce methylene blue or nitrates to nitrites either with or without 

 the addition of acetaldehyde. This may be due to the fact that oxy- 

 luciferin, which is also present, may be reduced more readily than 

 either nitrates or methylene blue and so is reduced first. 



Dubois" has described in Pholas a precursor of luciferin, which he 

 calls proluciferin, which is converted into luciferin by another en- 

 zyme, coluciferase. The proluciferin is not destroyed by boiUng and 

 the coluciferase will withstand a higher temperature than luciferase 

 and may be freed of luciferase in this manner. He cites an experi- 

 ment^^ to prove the existence of proluciferin and coluciferase in Pholas 

 but I have been unable to repeat this with Cypridina. One might 

 suppose that on allowing an extract of Cypridina (luciferase) to stand 

 in absence of oxygen, some proluciferin, assuming this to be present, 

 would be converted into luciferin which would give Hght if air was 

 admitted. But we can allow a boiled extract of Cypridina (contain- 

 ing no coluciferase) to stand with milk or muscle tissue suspensions 



^^ This experiment may also be performed with Pholas luciferase with a simi- 

 lar result. 



1* Dubois, Compt. rend. Soc. bioL, 1907, Ixii, 850; 1917, Ixxx, 964. 

 ^5 Dubois, Compt. rend. Soc. biol., 1917, Ixxx, 964. 



