6 The Stiidy of Animal Life PART i 



within the last quarter of a century, since the Challenger 

 expedition (1872-76), under Sir Wyville Thomson's leader- 

 ship, following the suggestions gained during the laying of the 

 Atlantic cables and the tentative voyages of the Lightning 

 (1868) and the Porcupine (1870), revealed what was 

 virtually a new world. During 3! years the Challenger 

 explorers cruised over 68,900 nautical miles, reached with 

 the long arm of the dredge to depths equal to reversed 

 Himalayas, raised sunken treasures of life from over 300 

 stations, and brought home spoils which for about twenty 

 years have kept the savants of Europe at work, the results 

 of which, under Dr. John Murray's editorship, form a 

 library of about forty huge volumes. The discovery of this 

 new world has not only yielded rich treasures of knowledge, 

 but has raised a wave of wider than national enthusiasm 

 which has not since died away. 



We are at present mainly interested in the general 

 picture which the results of these deep-sea explorations 

 present, of a thickly -peopled region far removed from 

 direct observation, sometimes three to five miles beneath 

 the surface a world of darkness relieved only by the living 

 lamps of phosphorescence, of silent calm in which animals 

 grow into quaint forms of great uniformity throughout wide 

 areas, and moreover a cold and plantless world in which 

 the animals have it all their own way, feeding, though 

 apparently without much struggle for existence, on their 

 numerous neighbours, and ultimately upon the small organ- 

 isms which in dying sink gently from the surface like snow- 

 flakes through the air. 



Far otherwise is it on the shore sunlight and freshening 

 waves, continual changes of time and tide, abundant plants, 

 crowds of animals, and a scrimmage for food. The shore 

 is one of the great battlefields of life on which, through 

 campaign after campaign, animals have sharpened one 

 another's wits. It has been for untold ages a great school. 



Leaving the sea-shore, the student might naturally seek 

 to trace a migration of animals from sea to estuary, and 

 from the brackish water to river and lake. But this path, 

 though followed by some animals, does not seem to have 



