ON LUMINOUS ANIMALS. 43 



Comte G- de Razoiiraouski. He states the number of these 

 luminous points to vary from 2 to 5*. 



I must however remark, that I never saw more than two but probably 

 of these himinous points, which were always upon the last ""^ "^*^^"* 

 ring of the body: and that the tii^ures, which accompany 

 the memoir of the Comte de Razoumonski, bear scarely 

 any resemblance to the insect they are intended to repre- 

 sent, from which we may fairly suspect him of inaccuracy 

 in other particulars, 



As far as my observation llgjli extended, the small sacs of They are nit 



luminous substance are not found in any species of lam- ^°™"^°" *^ 



•' *^ the genus, 



pyris, exce])t the glow-worm of this country, Thunberg 



mentions, that the lam pyris japonica has two vesicles on the 



tail, which afford light. 



The organs for the production of light in the genus Organ in the 

 elater are j-itqate in the corselet. These likewise consist ^^""^'"S ' 

 of a peculiar yellow substance, placed behind transparent 

 parts of the shell, which suffer the natural colour of this 

 substance to be seen through them in the day, and, when 

 illumina^^ed, give passage to the light. 



On dissecting the organs of light in the elater noctilucus, 

 I found that there is a soft yellow substance, of an oval 

 figure, lodged in the concavity of the yellow spots of the 

 corselet, which parts are particularly thin and transparent 

 in this species. This substance is so remarkably close in 

 its structure that at first view it appears like an inorganic 

 mass; but with a lens it is readily perceived to be com- 

 posed of a great number of very minute parts or lobules 

 closely pressed together. Around these oval masses the 

 interstitial substance of the corselet is arranged in a radi- 

 ated manner; and the portion of the shell, that immediately 

 corers the irradiated substance, is in a certain degree trans- 

 parent, but less so than that which lies over the oval masses; 

 it is therefore probable, that the interstitial snbstance in 

 this situation may be endowed with the property of shining. 

 A fasciculus of the muscles of the corselet arises in the in- 

 terior of the oval masses of the luminons substance, but 

 not apparently with any design ; as it contributes, with the 

 adjacent fasciculi, to move the anterior feet. 



♦ Mem. de la Soc. de Lausanne, Tom. u. 



In 



