(54 Journal New York Entomological Society. [Voi.iv. 
The spectrum of the light of the cucujo was found by Pasteur to be 
continuous. (C. R. French Acad. Sc. 1864, ii, p. 5 0 9 *) A. later ex¬ 
amination by Aubert and Dubois, showed that the spectrum of the light, 
examined by the spectroscope is very beautiful, but destitute of dark 
bands. When, however, the intensity diminishes, the red and orange 
disappear, and the green and yellow only remain. 
Heinemann studied the cucujo at Vera Cruz, Mexico. At night 
in a dark room it radiates a pale green light which shows a blue tone to 
the exclusion of any other light. The more gas or lamp light there is 
present, the more apparent becomes the yellowish green hue, which in 
clear daylight changes to an almost pure very light yellow with a very 
slight mixture of green. “ In the morning and evening twilight, more 
constantly and clearly in the former, the cucujo light, at least to my 
eyes, is an intensely brilliant yellow with a slight mixture of led. In a 
dark room lighted with a sodium light the yellow tone entirely disap¬ 
pears : on the other hand the blue strikingly increases.” As regards 
the spectrum he found that almost exactly half of the blue end is want¬ 
ing and that the red part is also a little narrower than in the spectrum 
of the petroleum flame. 
Prof. C. A. Young states that the spectrum given by our common 
firefly (Photinus ? ) is perfectly continuous, without trace of lines either 
bright or dark. “ It extends from a little above Fraunhofer’s line C, in 
the scarlet, to about F in the blue, gradually fading out at the extremi¬ 
ties. It is noticeable that precisely this portion of the spectrum is com¬ 
posed of rays, which while they more powerfully than any others affect 
the organs of vision, produce hardly any thermal or actinic effect. In 
other words, very little of the energy expended in the flash of the fire is 
wasted. It is quite different with our artificial methods of illumination. 
In the case of an ordinary gas light the best experiments show that not 
more than one or two per cent, of the radiant energy consists of visible 
rays; the rest is either invisible heat or actinism ; that is to say, over 
98 per cent, of the gas is wasted in producing rays that do not help in 
making objects visible.” (Amer. Nat. iii, 1870, p. 615). 
Panceri also remarks that while in the spectroscope the light of 
some Chcetopteri, Beroeand Pyrosoma, exhibit one broad band like that 
given by monochromatic light, that of Lampyns and Luciola is poly¬ 
chromatic (Amer. Nat. vii, 1873, P- 3 X 4 -) 
The physiology of insect-phosphorescence is thus briefly stated by 
Lang : “ The cells of this luminous organ secrete, under the control of 
the nervous system, a substance which is burnt during the appearance 
of the light; this combustion takes place by means of the oxygen con- 
