198 O. L. IXMAX. 



numerous small motile rod-shaped bacteria could be seen. 

 Inoculation of some of this material from the sand flea upon sea 

 water peptone agar to which had been added sufficient sodium 

 hydroxide to bring the pH to 8.1 resulted in the appearance of 

 numerous bluish-green luminous colonies of bacteria in from 

 twenty-four to thirty-six hours. These colonies were picked and 

 pure cultures obtained. By a series of transfers it was readily 

 determined that this bacterium in pure culture growing upon 

 artificial media of many different kinds would produce light if 

 the proper osmotic pressure and hydrogen ion concentration were 

 maintained. The optimum, minimum, and maximum salt con- 

 centrations and hydrogen ion concentrations for growth and 

 light production have not been determined but sufficient evidence 

 is at hand to show that growth and light production may take 

 place in a wide concentration of salts and hydrogen ion con- 

 centrations, the greater range from sea water being toward 

 fresh water and neutrality. Data on this phase of the subject 

 will be published in another paper. 



Thus it at once became evident that Giard and Billet were 

 unable to obtain luminous organisms upon artificial media 

 because they failed to adjust the hydrogen ion concentration of 

 their media which became neutral to acid when they added 

 peptones to sea water and in such a case good growth may be 

 obtained but no luminescence. 



Giard and Billet also did sufficient experimentation to satisfy 

 themselves that this bacterium was pathogenic to sand fleas. 

 They inoculated sand fleas and followed the cases through to 

 the death of the organisms which they claimed occurred more 

 quickly than normal sand fleas will die in the laboratory. 



The author repeated some of this work and found that it 

 was possible to transfer the bacteria quite easily from one 

 crustacean to another and that the administration of large 

 numbers of this bacterium to a sand flea did cause it to die 

 sooner than normal fleas. There were cases, however, when 

 transfer of bacteria or feeding bacteria seemed to have doubtful 

 effect and the sand fleas failed to become luminous. This 

 led the author to collect non-luminous sand fleas from various 

 habitats and isolate bacteria from the intestinal tract. In 



