LIGHT-PRODUCING ORGANISMS 13 



death, but also while living, so that their luminescence is 

 purely secondary. Giard and Billet (1889-90) succeeded 

 in inoculating many different kinds of amphipod Crustacea 

 {Talitrus, Orcliestia, Ligia) and isopod Crustacea (Porcel- 

 lio, Philoscia) with luminous bacteria, in some cases pas- 

 sing the infection from one to the next through nine 

 individuals. Curiously enough the bacterium did not 

 produce light on artihcial culture media but did when 

 growing in the body of the Crustacea, which were killed in 

 about seven days by the infection. The species of Talitrus 

 and Orcliestia might easily have been taken for truly 

 luminous animals if not carefully investigated. 



Tarchanoff (1901) has injected luminous bacteria into 

 the dorsal lymph sac of frogs with the result that the 

 animals continued to glow for three to four days, espe- 

 cially about the tongue. I remember once while collect- 

 ing luminous beetles in Cuba, I was astounded to find a 

 frog which was luminous. Expecting this animal to be 

 of great interest, I examined it further only to find that 

 the frog had just finished a hearty meal of fireflies, 

 whose light was shining through the belly with consider- 

 able intensity. 



Infection with luminous bacteria is especially liable to 

 occur in any dead marine animal. The flesh is an excellent 

 culture medium. I have seen non-luminous species of 

 squid, recently killed, covered with minute growing colo- 

 nies, quite evenly spaced, so as to closely resemble lumi- 

 nous species whose light is restricted to scattered light 

 organs over the surface of the body. 



Indeed Pierantoni (1918) has carried this idea to 

 extremes. He believes that in the luminous organs of 

 fireflies, cephalopods and Pyrosoma, luminous symbiotic 



