98 Observations upon Luminous Animals. 
Spallanzani relates, that the medusa which he examined - 
communicated the property of shining to water, milk, ‘and 
other fluids, on being rubbed or squeezed in them *. 
The luminous fled is in some instances confined to par- 
ticular parts of the body; and in others is diffused through- 
out the whole substance of the animal, 
In the scolopendra electrica, it appears to reside immedi- 
ately under the integuments. In the lynceus discovered by 
Riville, it is contained in the ovary. If I may judge from 
my own observations, every part of the body of the medusz 
is furnished with this fluid, as’ there is no part IT have not 
seen illuminated underdifferent circumstances ; but Spallan- 
zani aflirms that it is only found in the large tentacala, the 
edges of the umbella, and the purse or central mass 3 which 
he proved, he says, by detaching these parts successively, 
when they shone vividly, while the rest of the body neither 
gave light or communicated any laminous appearance to 
water fF. , 
Spallanzani discovered a mucous laminous fluid in the 
plumule of the pennatula phosphorea f. 
The phenomenon of animal light bas been attempted to» 
be explained in different ways. By many persons it was. 
formerly ascribed to a putrefactive process; but since the 
modern theories of conrbustion became known, it has been » 
generally believed to depend upon an actual inflammation | 
of the Juminous substance, similar to’the slow combustioi 
of phosphorus. Others have accounted for the luminous” 
effect, by supposing the matter of light to be accumulated, 
aud rendered latent under particular circumstanees, and af- 
terwards evolved in a sensible form. 
The opinion of the light of living animals being the con- 
sequence of putrefaction, is evidently absurd, and contra- 
dictory to all observation on the subject. It has been proved 
by the experiments of Dr. Hulme and others, that even the 
Juminous appearances of dead animals are exhibited only 
during the first stages of the dissolution of the body, and . 
‘that no light is emitted after putrefaction has really eom- 
menced. . 
Spallanzani, who was the most strenuous advocate for » 
the phosphorescent nature of animal light, stated that glow- 
worms shone more brilliantly when put into oxygen as j 
that their light gradually disappeared in hydrogen or im, 
azotic gas, and was instantly extinguished in fixed air; that 
* Spallanzani’s Travels in the Two Sicilies, vol. iv. 
4+ Memorin sopra le meduse fisforiche, Mem, della Suce Ital. tomo vii. 
t Mem. della Soc, Hal. tomo ti, 
‘ 
