CHAPTER III 



FLOATING CREATUREvS OF THE SEA 



The Nature of Floating Life — Memoir on Medusae Accepted 

 by the Royal Society — Old and New Ideas of the Animal 

 Kingdom — What Huxley Discovered in Medusae — His 

 Comparison of them with Vertebrate Embryos. 



AS the Rattlesnake sailed through the tropical seas 

 Huxley came in contact with the very peculiar 

 and interesting inhabitants of the surface of the sea, 

 known now to naturalists as pelagic life or " plankton." 

 Although a poet has spoken of the " unvintageable 

 sea," all parts of the ocean surface teem with life. 

 Sometimes, as in high latittides, the cold is so great 

 that only the simplest microscopic forms are able to 

 maintain existence. In the tropics, animals and plants 

 are abundant, and sometimes by their numbers colour 

 great areas of water; or, as in the drift of the Giilf 

 Stream, make a tangle of animal and plant life through 

 which a boat travels only with difficulty. The basis of 

 the food-supply of this vast and hungry floating life is, 

 as on land, vegetable life ; for plants are the only creat- 

 ures capable of buildmg up food from the gases of the 

 air and the simple chemical salts found dissolved in 

 water. Occasionally, in shallow or warm seas, marine 



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