OPTICS, CHEMISTRY, AND BIOLOGY 67 



and of a nucleus in a flame then becomes in- 

 telligible. 



The above considerations will help us to solve 

 the question of life in the infra-world. We have 

 already seen that there is no reason to postulate 

 the absence of any of the three states of aggrega- 

 tion of matter known to us. There is plenty of 

 light and heat in all probability. The conditions 

 of organic life are all present, and as regards geo- 

 logical time, the infra- world has much more of that 

 than we have, since what is a second in our world 

 is a thousand billion years in the infra- world. 

 There is, therefore, plenty of time for organic 

 evolution, and, indeed, for an evolution which trans- 

 cends all our present conceptions of its possibilities. 

 Yet a simple consideration will show that the evo- 

 lution of the infra-world has well-defined limits. 

 As far as we can judge, the infra- world is always 

 the same in its physical properties. Whatever 

 evolution is in progress there does not affect those 

 properties of the infra-world which we are able to 

 gauge, such as the constancy of the elementary 

 atoms and electrons. Our historical records go 

 back some 8000 years, which is 80 quadrillion 

 in Ira-years, and in all that immense time the 

 " evolution " of the infra-world has not sufficed to 

 change its apparent properties. Transferring this 

 analogy to our own world, it would mean that for 

 an almost inconceivable span of future time organic 



