ORIGIN OF LIFE ON THE EAETH. 129 



therefore must sometimes collide. A mass of 

 matter thus detached from an inhabited world 

 with germs attached to it might not experience 

 more violence than a piece of stone dislodged in 

 blasting ; and if it fell on an uninhabited world, 

 the adhering germs would in time stock that 

 world with life. 



It is true that masses of matter which might 

 possibly be fragments of disrupted planets are 

 scattered through the solar system, and there 

 is reason to believe that collisions between 

 planets, or suns and planets may occasionally 

 occur. We may also admit that aerolites 

 possibly contain qrganic remains ; and that 

 living germs carried to an uninhabited world 

 fitted for their reception would certainly de- 

 velope themselves. But granting all this, it 

 appears very doubtful whether any living germs 

 could be transmitted by aerolites from planet 

 to planet. 



The initial temperature of aerolites is that of 

 the interstellar spaces;* but on striking the 



* The absolute zero of temperature, or the total absence of all heat, 

 is stated by Murphy (" Habit and Intelligence," vol i. p. 16) to be 492 

 Fahr. below freezing ; but we have no means of ascertaining whether 

 such a temperature has any real existence in the Universe. 



K 



