SPECIFIC CHARACTERS. 21$ 



the change from a five-toed animal, we find that the 

 stages are all well marked, and of the thousands of 

 transitional forms between them nothing remains. 

 It must have taken very many generations, judging 

 from the slow modification of the horse family to- 

 day, to have modified a four-toed animal into a 

 three-toed one, and it is rather strange, if this 

 process did last such a long time, that no trace of 

 intermediate forms is found. 



If, in this case, the expected links are wanting, 

 still more forcibly is it true of others ; for nowhere 

 is there found a fossil history at all approaching 

 that which the theory would lead us to expect. It 

 is, of course, impossible to say whether the imper- 

 fection of the record is sufficient to account for this 

 lack. But it is certain that the transition links 

 have not yet been found, and no one has much 

 hopes that they ever will be. This was a surprise to 

 Darwin, and must be considered as an objection to 

 his theory ; and it has also been a surprise to others 

 who have wished to follow him in his belief in slow, 

 gradual modification. It has, moreover, led some 

 scientists to a different view of the origin of species, 

 according to which changes have been rapid and 

 short, while periods of rest have been very long. 



Specific Characters not always Useful. 



A difficulty of much more force than the fore- 

 going, is one which emphasizes the fact that all 

 variations, in order that they be acted upon by 

 natural selection, must be useful. A useless varia- 

 tion could never be selected ; but it is demonstrable 



