OBJECTIONS TO THE THEORY OF DESCENT. 331 



forms of life tend to supplant the old and unimprored 

 forms. 



By the theory of natural selection all living species 

 have been connected with the parent-species of each 

 genus, by differences not greater than we see between the 

 natural and domestic varieties of the same species at the 

 present day ; and these parent-species, now generally ex- 

 tinct, have in their turn been similarly connected with 

 more ancient forms ; and so on backward, always con- 

 verging to the common ancestor of each great class. So 

 that the number of intermediate and transitional links, 

 between all living and extinct species, must have been 

 inconceivably great. But assuredly, if this theory be 

 true, such have lived upon the earth. 



PLENTY OF TIME FOE THE NECESSARY GEADATIONS. 



Independently of our not finding fossil re- 

 Page 266. • i 1. ■ fl u 1 



mams of such infinitely numerous connecting 



links, it may be objected that time can not have suflSced 



for so great an amount of organic change, all changes 



having been effected slowly. It is hardly possible for me 



to recall to the reader who is not a practical geologist 



the facts leading the mind feebly to comprehend the lapse 



of time. He who can read Sir Charles Lyell's grand 



work on the " Principles of Geology," which the future 



historian will recognize as having produced a revolution 



in natural science, and yet does not admit how vast have 



been the past periods of time, may at once close this 



volume. 



When geologists look at large and compli- 



' cated phenomena, and then at the figures 



representing several million years, the two produce a 



