66 FROM AN EASY CHAIR 



owe their strange appearance to the birds having smeared 

 themselves with phosphorescent carrion or dead fish, the 

 luminosity of which is due to bacteria. The simplest 

 case of phosphorescence in living things is that of the 

 almost ubiquitous phosphorescent bacteria, minute 

 microbes like those which cause putrefaction. They 

 can be obtained and cultivated from almost any sample 

 of sea water. A thin slice of meat placed in a shallow 

 dish of salt water, so as to be barely covered by the 

 liquid, will in cool, damp weather, almost certainly 

 become covered with the growth of this phosphorescent 

 germ and appear brilliantly luminous. The popula- 

 tions of seaside towns have often been terrified by 

 all the meat in the butchers' shops suddenly becoming 

 thus phosphorescent. The growth may be cultivated 

 in flasks of salt broth. I have prepared such flasks, 

 which, when shaken so as to introduce oxygen, give 

 out a heatless blaze of light of a greenish colour, 

 brilliant enough to light up a room. I once found a 

 bone in a dog's kennel which was brilliantly phosphores- 

 cent owing to this bacterium. I kept it for several 

 days and showed it to Huxley as well as to other 

 friends. A certain kind of phosphorescent bacteria are 

 parasitic in the blood of sandhoppers, causing a disease 

 which kills them. The diseased sandhoppers shine like 

 glow-worms. I have found them abundantly on the 

 sea shore near Boulogne and near Trouville, but not 

 yet on the English coast. The bacteria can be seen 

 with the microscope and inoculated from diseased 

 luminous sandhoppers into healthy ones by using a 

 needle to prick first the diseased and then the healthy 

 creature. 



The animals of the sea are often provided with 

 secreting organs, producing a fatty body which can 

 be oxidised and made luminous at the pleasure of 

 the animal. Thus many marine worms and minute 

 sea-shrimps give out brilliant flashes of light. Jelly- 



