582 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
— depths which periodically comes near the surface.” 
t its luminosity the same author remarked ‘‘ when newly 
meets its body is brilliantly phosphorescent.” Kemp, how- 
ever, was not able to corroborate this statement by his obser- 
vations. During the course of nearly three years I had the 
the day and night, but except in the case of a single dead 
specimen none of them showed any signs of luminosity, nor 
was I able to distinguish any traces of luminous organs on the 
body of this fish. The particular a was taken in a 
beam-trawl in about 5 fathoms of water at Port Canning on 
: e spe 
a bowl of estuarine water for nearly six hours on the open 
deck, when my attention was directed to it by a faint light 
that was to be seen in the bowl. Ona careful examination it 
was found that the light was being emitted by the fish that 
had been left in the bowl. The light was of a faint bluish 
green colour and was not localized in any particular area 
rather the whole body of the fish was luminous. I suspected 
that the luminosity in this case was probably due to bacte- 
ria, particularly as the fish was already partially decomposed 
and was emitting a faint smell. Its body was covered 
with a shiny substance which on examination under the 
high power of a microscope was found to be teeming with 
bacteria. Working in an out of the way place like Port Can- 
ning and with my very limited knowledge of Bacteriology, it 
was not possible to proceed very far with the identification of 
the bacterium but on consulting the literature on the subject 
on my return to Calcutta I was able to decide from my roug 
sketches and notes that the bacterium belonged to the family 
Bacteriaceae and was, probably owing to the flagella at one 
end of te organism, one of the B. pflugeri group. 
Luminous bacteria have been known for a long time and 
it will elstly be not out of place to review the sige 
under which these organisms show phosphorescence :—(1) 
require a fair abundance of a nutrient medium like the dana 
bodies of fish, molluscs, etc., in which decay has just started, 
(ii) fair amount of moisture and a salty medium, (iii) tempera- 
ure of about 40° C. and (iv) abundant supply of oxygen. 
Jnder these circumstances the bacteria have been shown by 
direct experiments to produce a secretion which ignites in the 
presence of the abundant supply of oxygen and produces a 
faint peut 
therefore, clear that the Bombay Duck is not 
aely ‘phosphorescent for it does not possess any light-pro- 
ucing organs of the type found in other fishes, which are 
known to be luminous, but that the phosphorescence, whenever 
