568 SUPPLEMENT 
for a considerable time the phosphorescent property, and it 
was renewed by pouring fresh water upon it, even some time 
after it had ceased to shine. On the living animal, it is 
stronger in the state of contraction than in that of dilatation, 
which is easily explained, because it is the part which is 
particularly contractile, which exhales the phosphoric hu- 
mour. The light may be suspended for more than half an 
hour, which depends on the cessation of the oscillations, 
and nevertheless the phosphorescence continues, although 
to a degree much less intense, in the dead animal, even to 
putrefaction. The phosphorescence is increased by giving a 
commotion to the parts of the animal, or even by rubbing it 
with the hand. When it is living, it communicates to the 
water in which it is plunged, its phosphoric property, but 
half as much again in fresh water as in salt. 
Certain of these animals possess another property which is 
more hurtful, which is that of producing a very sharp pain, 
when they touch any part of our skin, which has occasioned 
them to be called sea-nettles. Dicquemare, who has made 
experiments in reference to this subject on himself, with the 
cyanea cerulea, relates the effects of them in these terms; 
“The pain is pretty nearly similar to that which is felt on 
touching a bunch of nettles; but it is stronger, and endures 
about half an hour. In the last moments reiterated stings 
are felt, but proportionally more faint. ‘There appears a con- 
siderable redness in all the part which has been touched, and 
swellings of the same colour, which have a white point in the 
middle. After the end of some days, when the pain is gone 
by, the heat of the bed will cause the blisters of the skin to 
re-appear.” This effect appears owing to a caustic humour, 
which issues from the skin of the medusa. Is it different from 
‘that which produces the phosphorescence ? 
This appears probable, since, as we have observed before, 
the species noticed by Spallanzani, which was eminently 
