138 OUTLINES OF BACTEEIOLOGY 



addition, the phenomenon is exhibited by certain animals and plants, 

 and of the latter a large proportion belong to the bacteria. The first 

 information with regard to bacterial phosphorescence was given us as 

 far back as 1853, when Heller declared that the luminosity of decom- 

 posing animal flesh was due to the presence of bacteria. No further 

 advance was made until Pfliiger in 1875 carefully investigated the 

 phosphorescent slime that he found on the body of a certain kind of 

 shell-fish. He demonstrated that the slime contained large numbers 

 of bacteria. By filtering a solution of the slime — dissolved in 3 per 

 cent, sea-water solution — and by showing that the filtrate was non- 

 luminous, whereas the filter paper glowed with phosphorescent light, 

 he demonstrated that the phosphorescence was caused by the bacteria 

 that had been stopped by the filter-paper, and not by something else 

 contained in the slime. Since this time our knowledge of the phos- 

 phorescent bacteria has been greatly extended; pure cultures have 

 been obtained, and the life-histories of twenty-eight of these organisms 

 have been accurately followed. They are found in all parts of the 

 world and in all climates. They are peculiarly adapted to the con- 

 ditions that obtain in the sea, for what traveller on the sea is not 

 familiar with the phosphorescence that is observed in the wake of a 

 ship, and the beautiful glow that sometimes lights up the waves as 

 they break on the shore t Eleven of the known twenty-eight species 

 have been obtained out of the sea, and doubtless there are many more 

 that have not yet been described. Again, these organisms are respon- 

 sible for the phosphorescence that is often observed in rotting fish, in 

 decomposing meat of various kinds and sometimes in rotting wood. 

 It is not uncommon on a dark night to see a beautiful luminous object 

 on the roadside, which on closer examination turns out to be the 

 remains of a decomposing fish. One of the phosphorescent bacteria is 

 parasitic on the blood of sandhoppers, causing a disease which kills 

 them. The stricken sandhoppers shine like glowworms, and by prick- 

 ing first a diseased creature and then a healthy one it is possible to 

 spread the disease, and consequently the phosphorescence. It is not 

 uncommon for butchers, especially in seaside towns, to notice that 

 their shops are lit up with a faint luminous glow when the lights are 

 turned out ; and it has been stated that a large percentage of the fish 

 sold in the markets at Trieste are phosphorescent in warm weather, 

 though apparently no harm accrues from their consumption. Again, 

 cooked potatoes in the first stages of decomposition often glow in the 

 dark. In the case of the meat, the fish, and the potatoes the phos- 

 phorescent bacteria are responsible. Finally, cases are recorded, but 



