1050 REPORT—1885. 
phosphorescent organs of Nyctiphanes norvegica, M. Sars, one of the same group. 
Professor G. O. Sars describes these organs as composed of a series of coloured 
elobules, the lens-like body of which acts as a condenser, and thus enables the 
animal to produce at will a bright flash of light in a given direction.? 
Marine phosphorescence has some of its most striking examples amongst the 
Tunicates. One of the best known instances is that of Pyrosoma, the light from 
which has been so graphically described by M. Péron, Professor Huxley, and other 
naturalists who have had an opportunity of observing it. It proceeds in each 
member of the compound organism from two small patches of cells at the base of 
each inhalent tube. These cells contain a substance resembling fat. Salpa has 
frequently been mentioned as a luminous form by many authors, but Delle Chiaje 
found that in the Mediterranean Salpa pinnata was not phosphorescent; and 
amongst the multitudes of Salpze which for some weeks abounded at Lochmaddy 
in North Uist, neither the former nor the Salpa spinosa of Otto exhibited this pro- 
perty, though a spark was occasionally seen in the nucleus in some specimens, pro- 
bably from the food. Giglioli likewise is doubtful concerning them, but in one 
instance a brilliant rose-coloured light appeared in the nucleus. Doliolwm,* on the 
other hand, shone with a greenish tint, while examples of Appendicularia which he 
encountered in various seas were chameleon-like in their luminosity, and often 
gleamed with great brightness. 
Various mollusks exhibit the property of phosphorescence. Fabricius ab Aqua- 
pendente mentions Sepra, Panceri Eledone, Adler Chama and ‘ Dactylus.’ The hest 
known is Pholas dactylus, which possesses two wavy bands and triangular organs 
of ciliated epithelium on the inner surface of the mantle. These secrete a lumi- 
nous substance, soluble in ether and alcohol, which illumines the excurrent 
water. The light is also maintained for along time during putrefaction, as in the 
ease of Thelepus. Panceri found that carbonic acid extinguished the light, but that 
air re-illuminated it, just as Johannes Miiller had previously observed in a vacuum 
and in air. The light is monochromatic, the bands having a constant place in con- 
nection with the solar spectrum (from line E to line F). 
Several Pteropods likewise contribute to the phosphorescence of the sea. Thus 
Giglioli noticed that a Cleodora gave out a vivid reddish light, while a Crises and 
a Hyalea were luminous at the base of the shell. He mentions also a large un- 
known Heteropod* in the Indian Ocean, which glowed with a reddish phosphor- 
escence. Amongst the Dermatobranchs, Phylirrhoé has the same property. 
Giglioli further found that Loligo sagittatus and a small Octopus gleamed all over 
with a whitish luminosity. 
Phosphorescence in living fishes appears to have been accurately observed 
within a comparatively recent date, though the luminosity of dead fishes has been 
known from very early times, and has been the subject of many interesting experi- 
ments such as those of Robert Boyle on dead whitings,* and Dr. Hulme on 
herrings.° Ido not mean to say that the literature of the so-called phosphorescent 
fishes is scanty, for it extends from the days of Aristotle and Pliny to modern 
times, but that the writers have had little reliable evidence in regard to living 
fishes to bring forward. Thus of upwards of fifty fishes entered by Ehrenberg in 
his list it is hard to say that one is really luminous during life. In many cases it 
is probable that the supposed phosphorescence of large forms, such as sword-fishes 
and sharks, has arisen from the presence of multitudes of minute phosphorescent 
animals in the water, just as the herring causes a gleam when it darts from the 
side of a ship. Professor Moseley, for instance, observed in the ‘ Challenger’ that 
when large fishes, porpoises, and penguins dashed through phosphorescent water, 
it was brilliantly lit up, and their track marked by a trail of light. The same 
feature is observed in hooked fishes, and it is known that fishermen are doubtful of 
1 <Challenger’ Narrative, Zoology, I. part ii. pp. 740-43. 
2 Vide also Mr. Murray’s observations in Prof. Herdman’s ‘ Report on the Tuni- 
cata of the “ Triton,”’ Trans. RS.L., vol. xxxii. p. 112. 
3 Op. cit. p. 497. 4 Phil. Trans. 1667, pp. 591-93. 5 Ibid. 1800, p. 161. 
