Observations upon Luminotis Animals. 97 
brane; but neither in them, or any of the other luminous 
insects, have I found an apparatus of this sort. The substance 
furnishing the light is uniformly applied to corresponding 
transparent parts of the shell of the insect from whence it 
is not moved; indeed a membrane, if it did exist, would 
have but litile effect in obscuring the light, and never could 
serve to extinguish it. The regulation of the kind and de- 
gree of the Juminous appearance does not depend upon any 
visible mechanism, but, like the production of the light it- 
self, is accomplished by some inscrutable change in the lu- 
minous matter, which in some animals is a simple operation 
of organic life, and in others is subject to the will, | 
Tt is worthy of remark, that in all the dissections I have 
made of luminous insects, I did not find that the organs 
of light were better or differently supplied with either 
nerves or air tubes, than the other parts of the body. The 
power ef emitting lght hkewise exists in many creatures 
which want nerves, a circumstance strongly marking a dif- 
ference between animal light and animal electricity. 
With the exception of the animals above mentioned, the 
@xhibition of light depends upon the presence of a fluid 
. matter. 
In the pholas dactylus, the luminous fluid is particularly 
_ evident, and in vast quantity; it is recorded by Pliny, that 
this fluid is like liquid ;hosphorus, and renders every ob- 
ject luminous with which it comes into contact. Reaumur 
also found that it was diffusible in water, or any other fluid 
_*in which the animal might be immersed *. 
The shining of the scolopendra electrica T have always 
observed to be accompanied by the appearance of an effusion | 
of a luminous fluid upon the surface of the animal, more 
particularly about the head, which may be received upon 
the hand, or other bodies brought into contact with the in- 
sect at the moment, and these exhibit a phosphoric light 
for a few seconds afterwards. This fluid, however, I never 
could discover in the form of moisture, even upon the 
clearest glass, although examined immediately with the 
most scrupulous attention by a lens: it must therefore be ° 
_ extremely attenuated. 
The same appearance has been observed during the illu- 
Mination of the nereis noctiluca by Fougeroux de Bon- 
daroy t. 
The animal discovered by Riville shed a blue liquor, which 
illuminated the water for a distance of two or three lines +. 
* Mem. de |’ Acad. des Sc. 17120" + Ibid. 1767, 
+ Mem. Etrang. de V Acad, des Sc. tome iii. 
Vol, 37. No, 154, Feb, 181). G Spallanzani 
