A PATHOGENIC LUMINESCENT BACTERIUM. 



O. L. IXMAX, 

 ANTIOCH COLLEGE. 



In 1889 Giard and Billet (i) found that a number of different 

 kinds of amphipod Crustacea (Talitrus, Orchestia, Ligia, and 

 others) gave off light. This luminosity was found to be caused 

 by the presence of luminous bacteria in the tissues of the crus- 

 tacea. In working with these luminous bacteria Giard and 

 Billet were able to transfer them from one marine crustacean to 

 another with ease and when grown on any marine crustacean 

 tried, the bacteria became luminous. The authors could not 

 get the bacteria to luminesce upon artificial media, although 

 they obtained good growth. They offered no explanation for 

 this failure and Harvey (2) pointed out that it seemed peculiar 

 that these organisms could not be grown on artificial media so 

 that they would produce light. 



The luminous bacterium isolated by Giard and Billet is 

 perhaps best known as Bacterium Giardi (Kruse) Mig., but 

 much work is still needed upon the classification of luminous 

 bacteria. 



In August, 1925, several luminous individuals of Orchestia 

 platensis (Kreyer) and Talorchestia longicornus (Say) were 

 brought into the laboratory of E. N. Harvey at the Marine 

 Biological Laboratory, Woods Hole, Massachusetts, and he 

 turned them over to the author for investigation. 



The sand flea chiefly studied was Talorchestia longicornus (Say) 

 which can be found buried in the sand just above the high tide 

 line during the daytime and feeding at the water's edge at night. 

 This species is about the size of a honey bee and while they can 

 be collected in June no luminous individuals have so far been 

 found until August. These sand fleas will live several days in 

 the laboratory if left in dishes of moist sand. 



When luminous sand fleas were broken open and the grayish 

 colored exudate mounted under the high power of a microscope, 



i97 



