26 THE WORLD OF THE SEA. 
small; 50,000 of them can live with the greatest comfort in a wine- 
glass of water! 
The noctiluca appears at first sight to be nothing but a small 
globule of transparent jelly. When under the microscope, it is found 
to have a spherical form, more or less regular, a little flat, and 
slightly umbilical beneath. In the centre of this protruding part is 
the mouth, which opens into a funnel-shaped cesophagus. Out 
of this opening comes a filiform tentacle, or feeler, like the stalk of 
an apple, which is very slender and mobile. . This tentacle appears 
to be tubular. Blainville supposes that it terminates in a sucker, 
so that it has something the shape of a trumpet. In some of its 
contractions the creature becomes reniform, or kidney-shaped, and 
NOCTILUCA MILIARIS. 
in others the tentacle disappears. The noctiluca exhibits here 
and there in its substance granules which are probably germs, 
and also some points of light. These appear and disappear with 
great rapidity; the least agitation makes them shine. Altogether 
these corpuscles of light form s5th or jth of the diameter of the 
creature. The noctiluca enamel the surface of the ocean as the 
constellations stud the firmament. 
The infusoria, as is now well known, are not the only animals 
which contribute to the phosphorescence of the ocean. This 
luminous state of the sea may also be caused by the meduse, star- 
fish, mollusks, nereida, crustaceans, and also certain fish, all which 
creatures evolve light just as the torpedo generates electricity. 
They multiply and diversify the effects of the phenomenon. The 
light which they produce is sometimes of a greenish tint ; some- 
