1880.] 245 



electric current in the trunk, or in the luminous organs. This excita- 

 tion determined an undoubted bright phosphorescence. 



Armed with the results of these experiments, I have proved (as 

 did Matteucci) that the presence of oxygen is absolutely necessary in 

 order to allow the action of the function. An insect prepared in the 

 manner first noticed, plunged into carbonic acid, azote or hydrogen, 

 and excited electrically in the gas, never became luminous. 



It may be thus considei-ed certain that the large granulous proto- 

 plasmic cellules constituting the parenchyma of the phosphorescent 

 apparatus, produce a substance which becomes luminous on contact 

 with the air emitted from the numerous tracheae that traverse the 

 apparatus. 



In order to know what that substance is, one must isolate and 

 analyze it. The resemblance of the glow to that of phosphorus has 

 caused several chemists to seek that substance in the luminous appa- 

 ratus, but their researches have been in vain, so that naturalists have 

 found themselves in the presence of two contradictory assertions. 

 This memoir proves that this contradiction is more apparent than 

 real, and that it results from a wi'ong interpretation of a common fact. 

 If one crush a glow-worm, one sees that traces of luminosity re- 

 main ; one imagines that they result from its apparatus, as from 

 lucifer matches, and that they are nothing else than the phosphorescent 

 matter stored up for the requirements of the insect. Experiences 

 thus gained are very defective ; let us consider them more methodi- 

 cally. If we content ourselves by dissecting a glow-worm by means 

 of needles, the fragments remain luminous during several hours. If, 

 on the contrary, we pound it in a mortar so as to destroy the cellules 

 themselves, the phosphorescence disappears immediately ; the collected 

 remains, exposed to pure oxygen, and submitted to electrical action, 

 remain absolutely dark. Thus a partial crushing permits phosphores- 

 cence to continue ; a complete crushing abolishes it absolutely. Ac- 

 cording to the hypothesis of a reserve of phosj)horescent matter, 

 complete crushing would be favourable by spreading the matter over 

 a large surface in contact with air, but what talies place is exactly the 

 contrary, the phosphorescence only persists if the apparatus itself is 

 divided into fragments. This proves that some groups of cellules re- 

 main intact, and continue their function. Dissection and contact 

 with air excites them, and their protoplasm, reacting under this 

 influence, produces the phosphorescent matter at the expense of the 

 materials it contains. If we kill these cellules by pounding them, life 

 no longer intervenes to put these materials in action, and to give them 

 the chemical conditions under which phosphorescence shows itself. 



