182 Papers from the Department of Marine Biology. 



worms which causes development of sea-urchin eggs (11). The chloro- 

 form or saponin might be supposed to cause the solution of granules or 

 globules (as can be observed in many cells) and the production of 

 light to be connected with this solution process. But I have already 

 given evidence (p. 178) to show that there are no granules unless ultra- 

 microscopic ones in the light-secretion of Cypridina, so that we must 

 look to another interpretation. 



Of many animal extracts tried on both concentrated and dilute 

 photophelein, none will give light. Neither have I been able to obtain 

 light with any chemicals or the oxidizing substances neutral H 2 O 2 , 

 Ba0 2 , ox blood alone or with neutral H 2 O 2 added, neutral potato juice 

 alone or with neutral H 2 2 , KMnO 4 , K 2 Cr 2 O 7 , FeCl 3 , or K 4 Fe(CN) 6 . 

 As already pointed out (p. 177), this result is the direct opposite of the 

 case in Pholas dactylus as described by Dubois. 



There is, then, in the non-luminous parts of Cypridina hilgendorfii a 

 large amount of photophelein, but only a small amount even in a closely 

 related non-luminous form. There appear to be only small amounts 

 in other luminous forms not closely related to Cypridina. For instance, 

 Cypridina photogenin will give a faint light with firefly photophelein, but 

 it is not nearly so bright as with Cypridina photophelein nor as bright 

 as that given by non-luminous Lepas extract. Unfortunately, no closely 

 related luminous crustacean was available, so that the degree of speci- 

 ficity of photogenin and photophelein could not be determined. At 

 least we may say that Cypridina photogenin and photophelein are 

 specific to a certain extent, but not in the strict sense of the word. 



The following tabulation gives the luminous animals which have 

 been tried with Cypridina in concentrated solution and the character 

 of the light resulting. None gives light in more dilute solution. 



Cypridina photophelein X firefly photogenin Faint. 



Firefly photophelein XCypridina photogenin Faint. 



Firefly photophelein Xfirefly photogenin Bright. 



Cypridina photophelein 1 X Cavernularia photogenin Fair. 



Cavernularia photophelein XCypridina photogenin Negative. 



Cavernularia photophelein X Cavernularia photogenin Negative. 



Cypridina photophelein XNoctiluca photogenin 2 Faint. 



Noctiluca photophelein 2 X Cypridina photogenin Faint. 



Noctiluca photophelein 2 XNoctiluca photogenin Negative. 



Owing to lack of material, the luminous fish Monocentris japonica 

 could be tested only in more dilute solutions, and with negative 

 results, viz: 



Cypridina photophelein X Monocentris photogenin Negative. 



Monocentris photophelein XCypridina photogenin Negative. 



Monocentris photophelein XMonocenlris photogenin Negative. 



'An extract, prepared with sea-water, as the dark juice of Cavernularia gives a brilliant light 

 with fresh water. 



2 All the Noctiluca extracts were made with n/1000 NH 4 OH to neutralize the acid of the Noctiluca 

 vacuoles. 



