430 Mr. C. W. Peach on the Luminosity of the Sea, 



Although at present I am unable to state the nature of the 

 luminous matter, this I well know, that animals and animal 

 matter, with probably small jointed algse, are always present 

 when the sea is luminous; and that when it is at its greatest 

 intensity, a peculiar state of the atmosphere may be noticed, 

 damp, soft, and close: a gentle rippling movement is also necessary 

 to disturb them, otherwise no light is emitted. I have noticed, 

 that should lightning and tempest follow unusual displays, and 

 this is frequently the case, all trace of them is lost for some time, 

 as if the electric discharge proved fatal. It is remarkable that 

 the light of the glow-worm is most brilliant at those times when 

 the luminosity of the sea is the greatest, thus showing that pro- 

 bably the luminous matter is of the same kind. There is still 

 another interesting fact connected with this peculiar state of the 

 atmosphere, for porpoises, also fish, such as pilchards, mackerel, 

 &c., which visit our coasts in shoals, are dashing and jumping 

 about, and sporting just before, or at the time when these lumi- 

 nous displays take place, as if acted upon by the same exciting 

 cause. 



When broad flashes are given out, myriads of minute crusta- 

 ceans are present ; frequently the Volvox plays a prominent part, 

 and is so abundant at times that the water is cloudy with them, 

 and often thought to be muddy. It is interesting to view the 

 minute Acalephse with a magnifying glass as they lie in the 

 landing net, to notice the luminosity of the ocelli and repro- 

 ductive organs — they are like so many brilliant lamps on gala 

 nights* I have watched them for seconds : to the naked eye the 

 light appears one, but the lens reveals their beauty, and shows 

 the multiplicity of their lights. After the light dies away, it 

 may be revived by plunging the object into fresh water ; it then 

 flickers brilhantly, being a beautiful blue at the centre, but gra- 

 dually ceases, and is lost, not again to be revived. I have seen 

 luminosity at all seasons of the year, and at all hours of the 

 night, and in bright moonlight. I have observed it until day- 

 light both in summer and winter, and even until overpowered by 

 strong daylight. Very young fish are probably luminous, and 

 I understand that the monk-fish or angler is like a lighted 

 lanthorn when in the water. I fancy that the luminosity of it 

 and other fishes may arise from gelatinous and other objects 

 which stick to them, rather than from any luminosity they 

 possess of their own ; of course I do not now speak of dead fish. 



I could have given many more instances which I have observed, 

 but from fear lest I should extend them too far, I pause, hoping 

 to renew the subject at some future time. 



I will now give a description of the objects figured. 



Plate XII. Figs. 1 to 9, 13 & 14, Diphtjdiee; the bell part of 



