Miscellaneous. 345 



elms (Tetraneura and Schizoneura), and those of the poplar and 

 pistachio (Pemphigus and Aploneura), or, at least, some of them, 

 have a period during which the egg alone exists. From the 1st to 

 the 6th January, however, the author found great numbers of 

 Vacuna dryoptrica, male and female, in copulation under the leaves 

 of an oak (Quercus pubescens). — Comptes Rendus, Jan. 12, 1880, 

 p. 80. 



Experimental Researches on the Phosphorescence of the Glowworm. 

 By M. Jousset de Bellesiie. 



Electricity, the nervous fluid, insolation, and the vital forces 

 have been invoked by turns as causes of phosphorescence. Finally 

 we have rested upon the existence of a phosphorescent matter 

 emitted by luminous animals, which appeared more probable. I 

 have thought it necessary to examine afresh this phenomenon in 

 the glowworm, because the investigations made by Matteucci, the 

 principal experimenter who has paid attention to the matter, were 

 by no means irreproachably conducted. In fact, neither this author 

 nor others have, in their experiments, taken into account the will 

 of the animal, or endeavoured to eliminate that cause of uncertainty ; 

 so that when they placed a glowworm in carbonic acid, for example , 

 they could not exactly determine whether the phosphorescence 

 ceased because the medium did not allow of its being produced, or 

 because the animal voluntarily refused to shine. It was necessary, 

 in the first place, to become master of the phenomenon, and for that 

 purpose to prevent the animal from shining at its own pleasure, 

 and force it to become luminous at that of the experimenter. With 

 this view, I remove the cephalic ganglia, which abolishes all sponta- 

 neous phosphorescence ; then I replace the voluntary excitation by 

 the passage of a moderate electrical current in the trunk or in the 

 luminous organ. This excitation causes, with certainty, a brilliant 

 phosphorescence. 



Possessed of this process, I proved, as Matteucci had done, that 

 the presence of oxygen is in fact absolutely necessary in order 

 that the luminous apparatus should perform its function. The 

 insect, prepared as just described, and immersed in carbonic acid or 

 inert gases, such as nitrogen and hydrogen, and electrically excited 

 in those gases, never becomes luminous. 



We may therefore regard it as certain that the large cells with 

 granular protoplasm forming the parenchyma of the phosphorescent 

 apparatus produce a substance which becomes luminous by contact 

 with the air conveyed by the numerous tracheae with which this 

 apparatus is furrowed. 



In order to know what this matter is, it was necessary to be able 

 to isolate it and analyze it. This has already been attempted. The 

 resemblance of the luminosity to that of phosphorus has led several 

 chemists to seek for that substance in the luminous apparatus ; but 

 their researches have been in vain, so that naturalists have found 

 themselves in presence of two contradictory assertions. The present 

 memoir shows that this contradiction is only apparent, and that it 



