6 W. C. M'Intosh on the Ahyssal Theoi-y of Light. 



demonstrate that one marine species which is luminous is more 

 jireyed on than another which is not. 



Some interesting features are presented by the Annelids. 

 ChcBtoptcrus norvegicus^ for instance, is a most beautifully 

 phosphorescent form, bright flashes being emitted from the 

 posterior feet ; but the most vivid luminosity is at a point on 

 the dorsum between the lateral Avings of the tenth segment. 

 Here the copious mucus exuded by the animal can be draAvn 

 out as bluish-purple fire of great intensity, which, besides, 

 now and then gleams along the edges of the wing-like pro- 

 cesses, at once illuminating the surrounding water and elicit- 

 ing the admiration of the observer. A very characteristic 

 odour, somewhat resembling that produced by phosphorus in 

 combustion, is given out by the animal during such experi- 

 ments. The common Harmothoe imhricata, again, discharges 

 bright greenish scintillations from the point of attachment of 

 each dorsal scale ; and thus, under irritation, the flashes are 

 arranged in pairs along the body, or in a double moniliform 

 line. The separated scales, also, continue to gleam for some 

 time, chiefly at the surfaces of attachment. If severely pinched, 

 the worm wriggles through the water, emitting sparks of green 

 light from the bases of the feet. The same phenomenon is 

 readily produced in a fragment either of the anterior or poste- 

 rior end of the body. The large Polynoe scolopendrina and a 

 Zetlandic Eunoa are similarly phosporescent, the light pro- 

 ceeding from the dorsal surface of the bases of the feet. A 

 EiisylUs common under stones and on the blades of tangles is 

 also highly luminous. Under irritation, a fine green light is 

 emitted from the ventral aspect of each foot. The scintilla- 

 tions seem to issue from many minute pores at each space, 

 flash along both sides of the worm posterior to the point of 

 irritation, and then disappear, a faint trace only being visible 

 for a few seconds. On one occasion, after a severe pinch, the 

 animal remained luminous behind the injured part for nearly 

 half a minute, while the surface of granular light on each 

 segment was larger than usual ; and in some instances those 

 of opposite sides Avere connected on the ventral aspect by a 

 few phosphorescent points. Moreover, for some time after, 

 mere shaking of the vessel caused a repetition of the brilliant 

 flashes. The body behind the irritated point had a decidedly 

 paler pinkish hue (under a lens) immediately after the emis- 

 sion of the luminosity. When at rest, a spark appeared 

 here and there at intervals. As in all such marine forms, 

 immersion in spirit elicited the luminosity, a moniliform band 

 of greenish phosphorescence (brightest at the tail) being 

 instantly produced on each side : at the end of five minutes 



