64 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. 509.) 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 Avith 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 red. 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 Ch?etopteri, Beroeand Pyrosoma, exhibit one broad band like that 

 given by monochromatic light, that of Lawpyi-is and Luciola is poly- 

 chromatic (Amer. Nat. vii, 1873, p. 314-) 



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- 



