134 LECTURES ON EVOLUTION m 



vast period of time; while the duration of life 

 upon the earth thus implied is inconsistent with 

 the conclusions arrived at by the astronomer and 

 the physicist. I may venture to say that I am 

 familiar with those conclusions, inasmuch as some 

 years ago, when President of the Geological 

 Society of London, I took the liberty of criti- 

 cising them, and of showing in what respects, 

 as it appeared to me, they lacked complete and 

 thorough demonstration. But, putting that point 

 aside, suppose that, as the astronomers, or some 

 of them, and some physical philosophers, tell us, 

 it is impossible that life could have endured upon 

 the earth for as long a period as is required by 

 the doctrine of evolution supposing that to be 

 proved I desire to be informed, what is the 

 foundation for the statement that evolution does 

 require so great a time ? The biologist knows 

 nothing whatever of the amount of time which 

 may be required for the process of evolution. It 

 is a matter of fact that the equine forms which 

 I have described to you occur, in the order stated, 

 in the Tertiary formations. But I have not the 

 slightest means of guessing whether it took a 

 million of years, or ten millions, or a hundred 

 millions, or a thousand millions of years, to give 

 rise to that series of changes. A biologist has 

 no means of arriving at any conclusion as to the 

 amount of time which may be needed for a 

 certain quantity of organic change He takes 



