XI.] 



PHOSPHORESCENT CRUSTACEA. 



441 



" If during winter one walks along the beach on the snow 

 which at ebb is dry, but at flood tide is more or less drenched 

 through by sea-water, there rises at every step one takes, an 

 exceedingly intense, beautiful, bluish-white flash of light, which 

 in the spectroscope gives a one-coloured labrador-blue spectrum. 

 This beautiful flash of light arises from the snow, before com- 

 pletely dark, when it is touched. Tlie flash lasts only a few 

 moments after the snow is left untouched, and is so intense, that it 

 appears as if a sea of fire would open at every step a man takes. 

 It produces indeed a peculiar impression on a dark and stormy 

 Avinter day (the temperature of the air was sometimes in the 

 neighbourhood of the freezing-point of mercury) to walk along 

 in this mixture of snow and flame, which at every step one takes 

 splashes about in all directions, shining with a light so intense 

 that one is ready to fear that his shoes or clothes will take 

 fire." 



BKETLK.S KKO.M PITLKKAJ. 



a. Carabns tmneaticollis Fschscholtz. (One and a half the natural size.) 



b. Alophus sj), (One and two-thirds the natural size.) 



On a closer examinati<jn it appeared that this light-jjheno- 

 menon proceeded from a minute crustacean, which according to 

 the determination of I'rof. W. LiLLJEBOliG belongs to the species 

 Metridia armata, A. Boeck, and whose proper element apjaears 

 to be snow-sludge drenched with salt water cooled considerably 

 under 0° C. First when the temperature sinks below — 10^ 

 does the power of this small animal to emit light ajjpear to cease. 

 But as the element in which they live, the surface of the snow 

 nearest the beach, is in the course of the winter innumerable 

 times cooled twenty degrees more, it appears improbable that 

 these minute animals sutfer any harm by being exposed to a cold 

 of from — 20° to - 30°, a very remarkable circumstance, as they 

 certainly do not possess in their organism any means of raising 

 the internal animal heat in any noteworthy degree above the 

 tem23erature of the surr(junding medium. 



