106 On a new kind of Phosphorescence observed 



the other; a mechanism very favourable for wounding any of the 

 enemies of this minute annelide. 



One of these annelides found at Chausey, in the testa of a balanus, 

 was nearly twelve lines long, and scarcely a quarter of a line in 

 diameter. Its feet were very numerous and approximate. The mo- 

 ment that I accidentally touched it, it commenced to creep rapidly, and 

 at the same time became so luminous, that I observed this luminosity in 

 spite of the glare shed b}'^ a lamp burning with a white flame. This 

 luminosity exhibited a well-marked and beautiful greenish hue. On 

 placing the animal in the dark, it appeared to be luminous throughout 

 its whole extent ; but upon examining it with a glass which magnified 

 five or six diameters, I immediately discovered that the light arrayed 

 itself in points which formed two parallel lines throughout the length 

 of the body, and corresponded to the feet of the annelide. These lumi- 

 nous points were very brilliant, and seemed to move about ; they 

 vanished when the creature was at rest, and reappeared so soon as a 

 slight excitement induced it to move again. 



Wishing to discover the phosphorescent organs with greater pre- 

 cision, I placed the annelide under my compressor. In this operation 

 it was divided ; but both fragments remained luminous. I first em- 

 ployed a lens which magnified only 10-15 diameters, and took care so 

 to arrange the light, that it was so obscure that I could at once distin- 

 guish the light produced by the annelide, and the spot whence it is- 

 sued. At the first motion which the animal made, I now saw each of 

 the luminous points I had formerly observed display itself under the 

 form of a star, whose body was formed by the base of the fleshy organ 

 whence the slender bristles spring. The rays were prolonged along the 

 muscles, which proceeded in all directions from this organ, like the 

 cordage of a ship, towards the different points of the ring. I had 

 abundant opportunity of examining it with all possible care, and I could 

 not discover the slightest trace of phosphorescence in any other part of 

 the animal. 



When I employed a lens which magnified thirty diameters, I had 

 great difficulty in discovering the sparks, their brightness being so much 

 diminished. I did, however, succeed ; and, by varying the amount of 

 illumination — sometimes dispensing with it, and again employing it — I 

 became quite assured that the light manifested itself only in those mus- 

 cles which were in action, and solely at the instant of their contraction. 

 Moreover, it scarcely ever extended throughout their whole length, 

 and appeared sometimes only towards their centre, and at other times 

 towards their points of attachment. It was always strongest in propor- 

 tion as the contractions were energetic. Finally, this light did not ap- 

 pear in a uniform manner, but as if composed of a great number of mi- 

 nute sparks ; and the impression it produced on my eye was in every 

 respect similar, though more feeble, to that which results from an elec- 

 trical discharge occurring through the medium of a great number of 

 small metallic plates placed in juxtaposition. 



