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PACIFIC SCIENCE, Vol. IV, April, 1950 
to ascertain the nature of the luminosity, and, 
if it was found to be luminous, to locate and 
describe the luminous organs. 
Cuvier and Valenciennes (1849), discuss- 
ing the economic uses of this fish, stated that 
they were informed "that when exposed to 
the air they give out during the night a 
living phosphorescent luminescence.” Cantor 
(1850) said, "It is very short lived . . . and 
the whole body becomes at certain seasons 
brilliantly phosphorescent.” Gunther (1880: 
584) stated "that when newly taken its body 
is brilliantly phosphorescent.” Kemp (1917: 
238), in his observations on specimens from 
the Matlah River, was not able to corrob- 
orate this statement. Hora (1934) also agrees 
with Kemp’s observations. Boulenger (1922: 
613) states that "H. nehereus when newly 
taken is brilliantly phosphorescent all over 
the body.” Kyle (1926) wrote of "the re- 
markable Harpodon which when caught be- 
comes brilliantly luminescent all over the 
body.” Norman (1931) stated "it is brilli- 
antly phosphorescent all over when newly 
caught without possessing any light produc- 
ing organs.” 
Whether these statements are the results 
of personal observation is not known, but 
they seem to refer to the condition of the fish 
after it has been caught or "newly caught,” 
whatever this may mean. 
Cuvier’s material was undoubtedly dead, as 
was Cantor’s, since the latter comments on 
the fact that the fish is short lived. None of 
the other statements refers to actual living 
material, and the expression "newly caught,” 
at least as far as Malayan material is con- 
cerned, may have no significance whatever 
for the following reasons. 
The Harpodon which are caught in Malaya 
are taken in nets which are set in estuaries, 
or between adjacent islands where there is a 
strong tidal stream during the ebb and flood 
of the tides. 
The nets are long bag- like affairs with 
meshes almost as fine as those of coarsely 
woven sackcloth. They lie on the bottom and 
are furnished with a wide-open mouth which 
faces the current. Through this mouth is 
swept into the nets, by the tidal stream, a 
mixed assortment of feebly swimming fishes, 
squid, Crustacea, jellyfish, and a miscellaneous 
assortment of debris from the land, such as 
leaves, twigs, etc. Once in the net there is 
no escape for those animals which cannot 
swim against the stream, and they remain 
crammed and compressed in the net by the 
constant addition of material which collects 
there. 
The nets remain there without attention 
until slack water, when they are lifted, emp- 
tied, and reset to face the stream as it reverses 
its direction with the change of tide. Most 
of the fishes and other animals are dead or 
dying when the nets are lifted, and only those 
caught last may be alive, since they are not 
subjected to anything but the pressure of the 
water. 
The time during which the nets remain 
unattended is about 6 hours, and most of the 
catch is taken during that 3 -hour period when 
the tidal stream flows strongest, which may 
occur an hour to an hour and a half after the 
setting of the net and last until an hour to 
an hour and a half before lifting it. There 
is a further delay in the handling of the catch 
when the fishermen have to lift the nets, 
dump the catch into a boat (incidentally 
dumping the dead on top cf the more recently 
caught, crushing and killing them in turn), 
and then row their catch ashore for sorting. 
This may account for a delay of at least an 
hour if not more, and it should be realised 
that by this time there is little chance of 
securing any living specimens of such a fee- 
ble, short-lived fish as Harpodon. "Newly 
caught” material may have been dead for 5 
to 6 hours at the most and for 2 or 3 hours 
at the least, and this fact is very important. 
There is no definite record of any observation 
on the luminosity of actually living material. 
In order to secure live specimens I had to 
