50 THE NEANDERTHAL SKULL. 



In reply to the very serious objection 

 to the Transmutation theory, such as bears 

 becoming whales in course of time, or pigs 

 growing into elephants, that no single case 

 of one species being evolved from another 

 having come within the observation ' of 

 man, Mr. Darwin replies that though 

 " Geology does not reveal any such finely 

 graduated organic chain and this perhaps 

 is the most obvious and gravest objection 

 which can be urged against my theory 

 the explanation lies, as I believe, in the 

 extreme imperfection of the geological record. 

 If my theory be true, it is indisputable that 

 before the lowest Silurian stratum was 

 deposited, long periods elapsed, as long as, 

 or perhaps far longer than, the whole 

 interval from the Silurian age to the 

 present day." One period he estimates to a 

 nicety, as follows: "I should infer that 

 the denudation of the weald (alone) must 

 have required 306,662,400 years, or say 

 three hundred millions." 



Darwin cautiously guards himself on 

 this, as on many other occasions, by that 



