14 THE NATURE OF THE PROBLEM 



Then came the normal sinking of the heavier elements to 

 the centre; the flinging out of the red-hot gases to the 

 circumference; the tentative encrusting of the central 

 molten mass, broken by the ceaseless volcanic spurts of 

 liquid fire, until the monster's energy was partly spent. 

 Then was formed the continuous solid crust, thinly encasing 

 the molten globe. Thicker and thicker it grew, as the heat 

 poured out into space. The combination of oxygen and 

 hydrogen gas, which we have learned to call water, con- 

 densed in the cooling atmosphere, as it does in the cloud 

 to-day, and fell on the crust. How long it fell only to be 

 shot back in hissing rushes of steam ; how long it foamed 

 and tossed, a boiling flood, on the heated surface, we cannot 

 say. The time came when a warm and placid ocean 

 clothed the whole surface of the globe. Probably from the 

 first the solid crust of the earth was uneven. Certainly at a 

 very early geological age comparatively small continents 

 were lifted above the water. But over the broad earth the 

 distant astronomer would have seen little but the steaming 

 mass of water. And somewhere in the depths or the 

 shallows it is not clear which of this vast primitive ocean 

 the first terrestrial living things appeared. Whence did 

 they come ? What were they like ? That is the problem 

 of the origin of life. 



It is important to remember that the only problem 

 discussed under this title by Professor Haeckel in the work 

 which Sir Oliver Lodge attacks is the problem of the origin 

 of life a hundred or a thousand million years ago ; the first 

 appearance of life on our planet. Sir Oliver says (p. 41) : 



