262 Master Minds of Modern Science 



creatures to be successful were open-sea creatures, half 

 plants, half animals, able to swim by means of a living 

 lash. In the open sea there still survive many creatures 

 of this kind — flagellates, as they are called — which swim 

 in this way, and seem still to hesitate between the animal 

 and vegetable kingdoms. 



As these creatures of the weed-belt increased in size 

 and numbers, some worked closer and closer to the shore. 

 These had to become hardy in order to withstand the 

 breaking surf. The tides, greater in those early days 

 than they are now, must have left many stranded high 

 and dry, and at length some became able to endure this 

 ordeal. They were shellfish similar to the limpets and 

 whelks which we all know so well. But not all the new 

 creatures were able to withstand the tumble of the waves 

 and the sweep of the tide on the beach, and of these some 

 ventured farther and farther out from the land, becoming 

 open-sea creatures. 



Others, again, worked their way down the sloping sea- 

 floor toward the ' mud line/ They were principally 

 soft-mouthed creatures such as sea-worms and sea- 

 cucumbers, which live upon soft particles — ' crumbs/ as 

 Sir Arthur calls them — that have sunk down from above. 

 Slowly these followed their food to greater and greater 

 depths, changing their form and habits so as to become 

 suited to life in the sunless chill of the deep sea. One 

 of the most interesting discoveries of the past century is 

 that life not merely exists, but is plentiful down to the 

 very bottom of the abysmal deeps such as are found off 

 the coasts of Japan and close to the Philippine Islands. 



Right up to the middle of the nineteenth century 

 naturalists spoke of the deep sea as being devoid of life. 

 It was not until i860, when a deep-sea cable was lifted in 

 the Mediterranean from a depth of six thousand feet and 

 fifteen living animals were found attached to it, that the 

 truth began to be suspected, but man had to wait until 



