192 ON THE ORIGIN OF THE PLANETAEY SYSTEM. 



process of formation, and will still continue to form 

 when our sun is extinguished, and our earth is either 

 solidified in cold or is united with the ignited central 

 body of our system. 



But who knows whether the first living inhabitants 

 of the warm sea on the young world, whom we ought 

 perhaps to honour as our ancestors, would not have 

 regarded our present cooler condition with as much 

 horror as we look on a world without a sun ? Consider- 

 ing the wonderful adaptability to the conditions of life 

 which all organisms possess, who knows to what degree 

 of perfection our posterity will have been developed in 

 17,000,000 of years, and whether our fossilised bones 

 will not perhaps seem to them as monstrous as those of 

 the Ichthyosaurus now do ; and whether they, adjusted 

 for a more sensitive state of equilibrum, will not con- 

 sider the extremes of temperature, within which we now 

 exist, to be just as violent and destructive as those of the 

 older geological times appear to us ? Yea, even if sun and 

 earth should solidify and become motionless, who could 

 say what new worlds would not be ready to develop 

 life ? Meteoric stones sometimes contain hydrocarbons ; 

 the light of the heads of comets exhibits a spectrum 

 which is most like that of the electrical light in gases 

 containing hydrogen and carbon. But carbon is the 

 element, which is characteristic of organic compounds, 

 from which living bodies are built up. Who knows 



