210 Papers from the Department of Marine Biology. 



ether or cold absolute alcohol for 12 hours without losing their power 

 to phosphoresce when the solvent has been removed and they are again 

 moistened. Colonies of luminous bacteria sometimes appear when the 

 filter paper is placed on a nutrient medium, even after such rigorous 

 treatment with ether and alcohol and other fat solvents. Buchner and 

 Gaunt (26) obtained similar results with the acetic-acid-forming bac- 

 teria of beer {Mycoderma aceti) . The dried acetic bacteria are not all 

 killed by extraction with acetone; moist bacteria are invariably killed.^ 



In testing the solubility in fat solvents, strips of filter paper contain- 

 ing the dried bacteria were placed in the solvents in sterile tubes for a 

 definite time at a definite temperature, the solvent completely removed, 

 and the filter paper tested for hght-production by adding sterile sea- 

 water. A plus mark (+) indicates fight, a minus mark ( — ) indicates 

 no fight. Controls, untreated with any solvent, always gave a good 

 fight. Table 13 gives the results. In the last column are similar 

 results obtained with the dried powdered luminous organs of the firefly. 

 The amyl alcohol and ethyl butyrate were completely removed by 

 washing with ether. 



The great majority of fat solvents extract nothing which is essential 

 to fight-production, as can be seen from the table. Chloroform might 

 have extracted something, as the material glows only faintly after 

 chloroform treatment. I have, however, evaporated the chloroform 

 extract to dryness in vacuo and added water as well as a water extract 

 of luminous bacteria (in itself non-lunfinous; possibly containing a 

 second necessary substance) to the residue without obtaining fight- 

 production. The same result was obtained with the residue of the 

 boifing alcohol extract, so that we must conclude that the chloroform 

 and boiling alcohol extract nothing, but rather destroy the photogenic 

 material. The temperature of boifing alcohol, 78.4°, is not destructive 

 to the photogen. These results are very similar to my previous results 

 on firefly material, as may be seen by inspecting the last column. The 

 photogen of the firefly is not weakened by chloroform or acetone or a 

 boiling mixture of equal parts alcohol and ether, but does suffer from 

 carbon disulphide. Otherwise the results are the same. 



The strips of filter paper moistened with sterile sea-water were then 

 transferred under sterile conditions to nutrient agar to see if colonies 

 of luminous bacteria would result. It was found that not in every 

 case, but in at least one experiment out of several tried, lununous 

 colonies were obtained after extraction of the material with ether, 

 alcohol, toluol, acetone, and benzol. 



I have already mentioned the fact that dried bacteria will glow if 

 moistened after extraction with cold (20°) absolute alcohol, and also the 



^I find that extraction of dried luminous bacteria with 95, SO, 50, or 35 per cent alcohol kills 

 them all and no new growths appear. Also if the moist bacteria are treated with a large excess 

 (50 volumes) of absolute alcohol or acetone for 10 minutes and then rapidly dried no growth is 

 possible. Bacteria so treated have also lost their power to phosphoresce when moistened. 



