290 STUDIES ON BIOLUMINESCENCE. XIV 



that very little luminous material is present in these forms at any one 

 time, but that it is manufactured continuously by the living bacterial 

 ceU. 



But in addition to the forms which may contain only small amounts 

 of luciferin and luciferase, or unstable luciferin and lucerferase, or 

 luciferase in endoenzyme condition, there are at least two groups of 

 animals which contain abundant luminous materials, whose light is 

 long lasting, whose cells may be easily broken up, and in which the 

 photogenic substances may be readily dried and give a bright light 

 on again moistening. These are the medusae, Mquorea forskalea and 

 Mitrocoma cellularia, and the pennatulids, Cavernularia haberi and 

 Ptylosarcus Sp.(?) especially the medusae. Mquorea and Mitrocoma^ 

 found at Friday Harbor, Washington, contain many clumps of 

 luminous cells about the rim of the umbrella at the base of the tenta- 

 cles. Under the microscope masses of yellow material can be seen in 

 the position from which the light comes, which probably are the 

 photogenic cells. Gentle rubbing of the region liberates abundant 

 luminous secretion which sticks to the fingers and which causes the 

 sea water to luminesce quite brightly. The rim of the umbrella is 

 easily cut away and this material, when squeezed through cheese 

 cloth, gives a permanent bright luminous extract whose light lasts 

 several hours. The animal itself luminesces only on stimulation. 



There is, then, in these medusae no lack of photogenic material. 

 The material is readily extracted and stable, since the light lasts for 

 several hours. Nevertheless, the luciferin and luciferase reaction 

 cannot be obtained with these forms despite many attempts and care 

 to guard against all sources of error. 



What is the reason for this negative behavior? Is luminesence of 

 jellyfish quite a different process from that in Cypridina, P holas, or ^re- 

 flies, which do give the luciferin-luciferase reaction? Or is the amount 

 of luciferase in these forms just sufficient to oxidize the luciferin which 

 is present and leave no excess in the extract? In Cypridina there is 

 enough luciferase in one animal to oxidize the luciferin of 100 animals, 

 but not an indefinite amount. Cypridina luciferase behaves as an 

 enzyme but is not a perfect example of a catalyst which should trans- 

 form indefinite amounts of substrate. There are, however, enzyme- 

 like bodies known, the peroxidases of plants, in which there is a definite 



