374 Miscellaneous, 



three times as long : this is as much the case with regard to the 

 separate luminous segments as for the entire worm. 



5. When this phosphorescent matter shines in oxygen or in the 

 air it consumes a portion of oxygen, the place of which is supplied 

 by the corresponding volume of carbonic acid. 



6. This same substance, in contact with oxygen, but having lost 

 the power of diffusing light, does not sensibly absorb oxygen, and 

 does not develope carbonic acid. 



7. Oxygen, mixed with hydrogen or with carbonic acid in the 

 proportion of 1 to 9, forms a medium in which the phosphorescence 

 continues for several hours ; we may then conclude that it is by the 

 alteration which has taken place in the phosjihorescent substance 

 that this leaves off shining after several days, having at first been put 

 into pure oxygen, the place of a portion of which was afterwards 

 supplied by carbonic acid. I analysed the hydrogen in which I had 

 kept several glow-worms for four-and-twenty hours ; the insects had 

 shone but a few minutes : this is the case if the gas is pure, if we 

 operate over mercury, and if care be taken in filling the bell-glass to 

 turn it over two or three times in order to remove the air which adheres 

 to the glow-worms. In this hydrogen gas I found that the volume 

 had increased by a small quantity, and in treating with potash I 

 ascertained that this excess was owing to carbonic acid furnished by 

 the glow-worms ; and this took place either because there w'as a re- 

 sidue of oxygen in their trachea which had combined with the carbon 

 and changed into carbonic acid, or because the insects contained this 

 acid already formed ; \vhen only the luminous segments are put into 

 hydrogen, with precaution, they continue to shine but for a few 

 seconds, and the gas undergoes no change. 



8. Heat, up to certain degrees, increases the light of the phospho- 

 rescent matter ; the contrary takes place from cold. 



9. When the heat is too great the phosphorescent substance is 

 altered, and the same takes place with this substance when exposed 

 to the air or to some gases for a certain time ; it is necessary, how- 

 ever, that it should be separate from the animal. 



10. ITiis phosphorescent matter thus altered is no longer capable 

 of gi^^ng light or of becoming luminous. These conclusions evidently 

 establish the nature of the phsenomenon ; the production of the light 

 in this insect is altogether dependent on the combination of the 

 oxygen with the carbon, which is one of the elements of the phos- 

 phorescent matter. Now it is important to inquire how the phospho- 

 rescence takes place in the living animal ; what circumstances cause 

 it to vary ; and what is the structure of the phosphorescent substance 

 and of the parts which surround it. — Comptes Rendiis, Aug. 14. 



OBSERVATIONS ON DE. MARTIN BARRY's MEMOIR ON FIBRE. 

 BY PROF. MOHL. 



It has already happened to several microscopic observers, that they 

 have fancied they saw in their investigations the most minute parts 

 of organized bodies, and have imagined that they had detected pri- 

 mitive formations in the form of fibres, globules, &c., and then 

 wherever they looked they again found them, and consequently gave 



