Marvels of the Universe 



Photograph of a self-lun 



ant fish. 



a whale will leave a belt of glowing greenish 

 luminosity spreading far behind the animal to 

 a hundred feet in length. The origin of this 

 light has been accounted for by the presence of 

 countless myriads of Pyrosoma and Noctiluca, 

 which, though microscopically small, are 

 capable, like the glow-worm and the fire-fiy, 

 of giving forth a light, which, in proportion to 

 their size, is amazingly brilliant. 



And, loosely, perhaps, because of its re- 

 semblance to the pale glow of phosphorus in the dark and the appearance of dried or stale fish, 

 when seen in a dark place, which lambent flame will come off upon the fingers like some forms of 

 electricity, but without the shghtest sensation to the experimenter ; it has become the practice to 

 call this glow phosphorescence. Therefore, without committing ourselves to any statement as to the 

 origin or causes of fluctuation of this sea-light, we will use the trivial name where necessary. 



It is not even now known how far down the illumination of the sea by the minute creatures 

 named extends, but comparatively recent discoveries go to show that some of the denizens of those 

 vast depths carry about their own electric light installation, so to speak, being able to render 

 themselves luminous or the reverse at will. To what extent this faculty prevails is unknown, 

 because our knowledge of life in those awful depths is very limited ; but it may be noted that the 

 majority of the ab3'ssal fish have no means of lighting themselves up, as it were. This incapacity 

 is not confined to the more hideous or horrible-looking among them, but some quite innocent- 

 looking creatures are left in the dark, owing to the absence of any system of lighting on their 

 bodies. 



It must also be borne in mind that the glow which is noticeable in many surface fish, pervading 

 the whole body of the creature, has nothing in common with the extraordinary system of animal 

 lighting which we are about to consider, which is without any exaggeration more akin to an 

 electrical installation than aught else. Let us take, for instance, the very queer little fish with the 

 euphonious title of Collettia rafinesquei, which was caught not far from the coast of the United 

 States in a depth of nearly eighteen thousand feet. It has enormous eyes in proportion to its body, 

 and a shape not unlike a mullet, but on its underside it is provided with a number of tiny lamps, 



little globular points arranged in a certain sequence of longi- 

 tudinal lines from gills to tail with short spurs running up the 

 sides. 



It is evident from the arrangement of the light vesicles on 

 this fish that it does not use its power for hunting purposes. 

 Beyond that, being, as we are, completely in the dark as to its 

 habits, we can say little except that it swims serenely about, 

 shedding a beneficent glow beneath itself to assist other fish in 

 their avocations. It also affords a proof of the wide-spread 

 habitat of all deep-sea fishes, since other examples of this fish 

 ' have been found in the Mediterranean. 



Come we now to a stately creature with a no less magnilo- 

 quent name, Mthroprora effulgens. In shape this fish has 

 nothing out of the common, but in complete justification of 

 his poetical name, he bears upon his snout a luminous mass 

 .-.,,,,,, , „ which is indeed a " flashing light ahead," warning all and 



The head of a fierce-looking fish: the o o ■ o 



photograph shows clearly four of the suudry of his approach. Dowu the median line of his body on 



phosphorescent spots which line the body -,, ■ -. c- , ,i, i-ii , ■, 



on each side. either Side runs a row of incandescent plates, while beneath 



