The water when placed in a tumbler and agitated gave out sparks, but a small portion in a watch-glass scarcely ever was luminous.
Ehrenberg states that these particles all retain a certain degree of irritability.

My observations, some of which were made directly after taking up the water, gave a different result.

I may also mention, that having used the net during one night, I allowed it to become partially dry, and having occasion twelve hours afterwards to employ it again, I found the whole surface sparkled as brightly as when first taken out of the water.

It does not appear probable in this case that the particles could have remained so long alive.
On one occasion having kept a jelly-fish of the genus Dianaea till it was dead, the water in which it was placed became luminous.

When the waves scintillate with bright green sparks, I believe it is generally owing to minute crustacea.