32 M. Peters on the Light of Lan/pt/ris Italica. 



extent, both open into a rectum of a very delicate structure. It was 

 probably this delicate structure of the extremity of the intestinal canal 

 that made Carrara suppose that it communicated with the luminous ap- 

 paratus ; but with the exception of the alternate dilatation of this con- 

 duit, we find no bubble of air throughout its whole extent. The phos- . 

 phorescent organ is even separated from the intestines by a cushion of 

 white fat, which can be easily raised, when we get a view of this organ, 

 the colour of which is sulphur-yellow. On the two penultimate segments, 

 and partially even on that which precedes them, we notice a multi- 

 tude of tracheal ramifications converging, and these, when examined 

 ■with the glass, appear to consist of round corpuscles closely pressed 

 against each other, in such a way that the whole presents some resem- 

 blance to the electrical organ of the Torpedo, although I am unable to 

 determine the degree of resemblance that may exist between the two 

 organs. If a stronger magnifying power be used, we notice in the lumin- 

 ous part regular series of brownish corpuscles, having a silvery white 

 point in the middle, which, seen with a still higher magnifj-ing power, 

 presents itself under the appearance of small ramifications. When a 

 compound microscope is used, we then distinctly see that the whole or- 

 gan consists of a regular bed of small spheres, into which the tracheal 

 ramifications penetrate, and then spread themselves in the most elegant 

 manner, forming, so to speak, the skeleton. Besides that, we see deve- 

 loped in this delicate membrane of small spheres a quantitj' of molecules, 

 to which is attached the luminous extremity : the latter, by means of the 

 considerable interlacement of aerial vessels, may receive an enormous 

 quantity of air at once. 



The luminous substance itself is of a yellow colour; the intensity of 

 the light is in the direct ratio of the change of the yellow colour of the 

 organ, which can be easily shewn when we bring the latter in contact 

 with water, I was unable to trace the progress of the nervous system in 

 it, because the principal branch consisted of a filet of extreme tenuity. 



It must not be here supposed that we witness, in these spheres pro- 

 ducing the phosphorescence, a transformation of the ordinary corpuscles 

 of the fatty matter, for the former are completely different from the lat- 

 ter, as well in respect of form as of colour ; the same in all their contours, 

 such as they are observed by the microscope ; but it appears to me likely 

 that the principal matter entering into their structure, independently of 

 the ramifications of the truchere, is a fatty matter, and that it is to the 

 latter the luminous and phosphorescent substance is attached. 



It therefore appears to me demonstrated, saj'S M. Peters in conclusion, 

 that the luminous organ in Lampyris Italica, has the most intimate rela- 

 tion with the organs of respiration ; but I cannot determine if this is 

 equally the case with the sexual organs." * 



• From L'Institut. No. 432, p. 127, where the paper is translated from 

 Archiv. flir Physiol., &c., 1841, p. 229. 



