Bacteria 
injected into the patient ; it is supposed that this serum 
contains antitoxins which will help the sick person to 
resist his bacterial foes. For other details on this 
interesting subject the reader must be referred to, e.g., 
Muir and Ritchie.* 
There are so many other interesting questions con- 
nected with the world of bacteria that it is difficult to 
make a selection. 
There are at least twenty-six species of bacteria and 
some twenty kinds of fungus which are phosphorescent, 
so that the algz are not alone in this curious accom- 
plishment, 
Amongst the fungi, the commonest species is Agaricus 
melleus, which is capable of making an old dead tree 
glow after a very strange and ghostly manner. The 
light from cultures of phosphorescent bacteria is not of 
a dazzling character, but a quiet phosphorescence with 
faint tints of blue green or violet. Even in broad day- 
light one can distinguish it in the dark corner of a room, 
Living lamps have been made by growing these bacteria 
on gelatine in glass flasks. Professor Dubois had one 
at the Paris Exhibition in 1900, and Professor Molisch 
had a splendid specimen at the Carlsbad Congress 
of 1902. 
This lamp will remain alight for fourteen to twenty- 
one days, and can be used as a night light, or even 
to read one’s watch or very large print. One can even 
take a photograph by it, but yet it is not likely to be 
a good commercial light, for one would require some- 
thing like 2000 square yards of bacterial cultures to 
get one candle-power.® 
If the reader wishes to see these curious phosphores- 
cences, it is only necessary to rub fish (not too fresh) 
with a piece of raw butcher’s meat and place it in a 
3 per cent. solution of common salt. 
59 
