202 
cludes from his numerous observations on this 
subject, that, in marine animals generally, the 
coats of the stomach and intestines are the 
light-giving organs. 
In insects the seat of luminousness is more 
satisfactorily ascertained, and is found to vary 
very much in different species and tribes. 
The eggs of the lampyrides are said to be fre- 
quently seen luminous, and to continue so for 
several days after being deposited. In the 
states of larva and chrysalis also, the same in- 
sects emit light most vividly when touched, 
chiefly from the posterior segments of the 
body. On being much irritated, the whole of 
the chrysalis seems to shine in a slight degree, 
and for a short time. 
In the perfect female glow-worm of this 
country, the light is emitted chiefly from the 
inferior and lateral surfaces of the two or 
three last segments of the abdomen. The 
male of the same species presents only two 
small luminous points on the sides of one of 
the segments. hen the light-giving surfaces 
of the female lampyris noctiluca are narrowly 
examined, it may be seen that, on the penul- 
timate and antepenultimate segments, they pre- 
sent bands of a bright greenish-yellow light, 
which are abruptly terminated towards the 
trunk by an irregularly waved line; and that 
from the rest of the same segments there 
issues a fainter light of a pale green colour. 
There is also a little light given out by the 
posterior extremity of the dorsal line. In 
L. italica, the two last segments are wholly 
and nearly equally luminous. Most of the 
glow-worms in displaying their light recurve 
their tails upon their backs, so as to bring their 
luminous surfaces into view. 
Elater noctilucus gives out light principally 
from two points of the thorax, which are some- 
what raised, and of an oval shape; but it has 
also two light-giving organs situated beneath 
the wing-cases, which are not seen except 
when the insect is flying. Light is also 
emitted from the internal parts through the 
interstices between the abdominal segments. 
In bupestris ocellata, the light is emitted 
from certain yellow spots upon the elytra: in 
scarabeus phosphoricus from the belly: in 
chiroscelis bifenestrata, (a New Holland insect) 
from two oval, hairy, reddish spots on its 
second ventral segment; while, in pausus sphe- 
rococcus, a dim phosphoric light issues from 
its singular hollow globular antenne. 
Macartney says that he always observed the 
shining of scolopendra electrica to be accom- 
pee? by the appearance of an effusion of a 
uminous fluid upon the surface of the animal, 
perler'y about the head. On touching this, 
is finger and other bodies received on their 
surface a phosphoric light, which continued to 
shine for a few seconds, and then died away ; 
and yet he could not see any actual moisture, 
even upon smooth glass, although examined 
immediately and attentively. 
The researches of Treviranus have led him 
to conclude that there is no special luminous 
organ in insects; but that the generally dif- 
fused fatty matter is the seat of the function, 
ANIMAL LUMINOUSNESS. 
by which the luminousness is produced. He 
concludes, therefore, that, when the air has ree 
access to the interior of the body through the 
respiratory tubes, the whole of the internal 
organs give out light; and that this is not seen, 
excepting at certain points of the surface 
merely because the integuments are not trans- 
lucent. ,.* 
V. Anatomy of light-giving organs.—T| 
accounts of examinations of these organs 
have hitherto been published are rather imp 
fect. This appears to be owing chiefly tot 
fact that the organs themselves are of ¥ 
simple structure and furnish no materi 
lengthened description. So much so a’ 
in insects, that one would be inclined 
to conclude with Treviranus, that they a 
nothing but the common fatty or inter 
substance which fills up the bodies of i 
slightly modified by the presence of so 
phosphoric matter, were it not for the fa 
particularly observed by Macartney, 
the glow-worm, the luciferous organs are: 
sorbed after the season for their use is p 
and their places supplied by the u 
stance. The following are the results ob 
by this naturalist and by Spix from their ¢ 
sections of the glow-worm, the fire-fly, a 
the lantern-fly. : 
In the glow-worm, there is spread over t 
internal surface of the segments of the 
men a yellowish substance of the consi 
of ponte, which is thickest in the middle 
each segment, and terminates near each m 
by a wavy outline. It is of a closer 
than the fatty matter, but otherwise re 
it. Besides this substance, the last segn 
furnished internally, just beneath the mo: 
transparent part of its integument, with twe 
small round bodies, lodged in depression: 
which contain yellow matter of more close 
homogeneous texture. Miiller and 
describe these round bodies as “ two small 
ovate sacs, composed of thready membranes 
and filled with a soft yellow pasty matters 
Under the microscope, they appeared to Macait 
to be composed of numerous branching fila 
ments, with minute granules adhering to them 
It is from points of the surface correspondin 
to the situation of these round bodies that th 
light is most constantly and most bright 
emitted. When dry, these luminous organ 
have somewhat of the appearance of gum 
The dried matter is translucent and yellowis 
becomes darker on being kept, and appears 
be granular in its structure. Itss gl 
vity is a little greater than that of water. 
In the fire-fly, the internal concavities of the 
yellow spots of the corselet, whence the 
proceeds, are filled with a soft yellow sul 
stance, oval in shape, and of ee uniforn 
consistence and density. This, under the 
croscope, appears to be formed of a 
number of very minute parts or lobules, closely 
pressed together. Around these oval bodies, 
the fatty matter of the corselet is arranged | 
a radiated manner. Spix describes the sam 
organs as “ yellowish glandular masses, into 
which many branches of the trachea enter.” 
2 
rod 
ae 
4 
te. 
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#2. 
