Akademie der Wlssenschaften zu Berlin. 411 
them to heat ; he punctured, cut, and tore them, but in spite of all his efforts, 
never could discern the smallest spark of light. The ovaria of some were 
full, and of others undeveloped. The same remarks apply to the undoubted 
specimens of Medusa aurita which he obtained in the Red Sea. Humboldt, 
in his voyage to the Brazils in 1814, caught several specimens off Teneriffe, 
which were peculiarly luminous. On being laid on a tin plate, they emitted light 
when it was struck. The same phenomenon occurred the moment that the 
wires of a galvanic battery were joined. Ehrenberg therefore supposes, from the 
totally different results which he always obtained, that what is called the Me- 
dusa aurita of the Atlantic must be a very nearly allied species to that found 
in the East Sea, and the Red Sea, though hitherto called by the same name. 
After a violent storm at Heligoland in 1835, numbers of Medusa was thrown 
ashore, and amongst others, Cyanea capillata, Chrysaora isoscela, Cyanea La- 
marckii, and a small new species, to which Ehrenberg gave the name of Cyanea 
Heligolandia. None of them emitted any light, but thinking that a difference of 
temperature might have occasioned the disagreement of his own observations 
with those of Humboldt, they were placed in warm water, but without effect. 
No infusoria were found in the luminous sea water at Heligoland, but quantities 
of morsels of gelatinous matter, often torn and ragged, which emitted light, and 
small gelatinous globules, with jagged edges, occurred similar to those before de- 
scribed, which he obtained in the Red Sea. They all emitted similar sparks, on 
pouring a portion of brandy, spring water, or hot sea water upon them. They 
were evidently alive, swam slowly, and amongst them he easily detected numbers 
of Medusa or Noctiluca scintillans. On shaking the glass containing them a 
few sparkled, but not all. During his stay at Heligoland, the author often ob- 
served, as it were, chains of luminous matter floating about in the sea, some of 
which, with some difficulty, he succeeded in obtaining. He then proceeded im- 
mediately to his house, and examined them without delay. They proved to be 
masses of luminous Medusa, detached and torn by the violence of the sea, but 
he found that they continued to emit light, only as long as they retained vitality. 
Some of these fragments will live for a week, while others die, and are decom- 
posed in a very short time. He has no doubt that the difference of opinion 
which exists on this branch of the subject has arisen from collectors having 
delayed to examine such luminous water, till the morning after it was taken, 
when the torn particles may be already dead, and incapable of emitting any 
other light than what proceeds from decaying fish, &c. The sea animal which 
gives out the brightest light of all is the Nereis cirrigera, one of the Annellides. 
They live together in large masses, in branching sea- weed, and when portions 
of it are thrown ashore they continue to live, and shine with great brilliancy for 
many days. It is difficult, from the momentary nature of the spark given out 
by the Medusa and infusoria, to perceive in what way the light is generated. 
In the Photocharis, it is very visible. On each side of its feet, it is furnished 
with two fleshy threads, the upper one longer than the other, and not so thick 
but strongly resembling each other in their internal structure : a circulation of 
globules of blood is perceptible in each. The light always proceeds from these 
cirrhi, and particularly from the under or thicker one, which lies between the 
rough tubercles of the foot, and the upper one. A few detached sparks first 
appear on each cirrhus, which gradually increase till they are both illuminated. 
They then proceed over the back, till the whole animal shines with a greenish 
