INFUSORIAL ANIMALCULES. 1-11 



oil is poured on its surface, or underneath the receiver of an air-pump, 

 they are killed. They will live in water where poisons which mingle 

 mechanically, not chemically, are infused. But all sudden transitions 

 are destructive, as the mixture of sea with fresh water ; still, if the 

 change be gradual, they will adapt themselves to the new element and 

 survive. The phosphorescent appearance of the ocean, arising chiefly 

 from the presence of animalcules, is thus described by Darwin : " While 

 sailing a little south of the River La Plata, on one very dark night, the 

 sea presented a wonderful an,d most beautiful spectacle. There was a 

 fresh breeze, and every part of the surface, which during the day is seen 

 as foam, now glowed with a pale light. The vessel drove before her 

 bows two billows of liquid phosphorus, and in her wake she was fol- 

 lowed by a milky train. As far as the eye reached, the crest of every 

 wave was bright ; and the sky above the horizon, from the reflected 

 glare of these livid flames, was not so utterly obscure as over the vault 

 of the heavens. Near the mouth of the Plata some circular and oval 

 patches, from two to four yards, shone with a steady but pale light, 

 while the surrounding water only gave out a few sparks. The appear- 

 ance resembled the reflection of the moon or some luminous body, for 

 the edges were sinuous from the undulations of the surface." 



Naturalists consider the phosphoric light of the marine animalcule 

 to be the effect of vital action. The sparks are intermittent like the 

 fire-fly; they measure from the 12,000th to 100th of an inch in size. 

 Captain Scoresby found that the broad expanse of waters at Greenland 

 was nearly all discoloured by animalcules, and computed that of some 

 species one hundred and fifty millions would find ample room in a 

 tumbler of water. Mr. Gosse thus describes the luminous appearances 

 presented by a closer inspection of these minute animalcules : " Some 

 weeks afterwards I had an opportunity of becoming acquainted with 

 the minute animals, to which a great portion of the lumiuousness of the 

 sea is attributed. One of my large glass vases of sea- water I had ob- 

 served to become suddenly at night, when tapped with the finger, 

 studded with minute but brilliant sparks at various points on the sur- 

 face of the water. I set the jar in the window, and was not long in 

 discovering, without the aid of a lens, a goodly number of the tiny jelly- 

 like globules of Noctilucu miliaris swimming about in various direc- 

 tions. They swam with an even gliding motion, much resembling that 

 of the Volvox globator of our fresh-water pools. They congregated in 

 little groups, and a shake of the vessel sent them darting down from 

 the surface. It was not easy to keep them in view when seen, owing 

 rather to their extreme delicacy and colourless transparency than to 



