6 2 THE DARWINIAN THEORY 



a short time ago. Speaking of this point, Darwin 

 says: "We shall perhaps best perceive the im- 

 probability of our being enabled to connect species 

 by numerous fine intermediate fossil links, by asking 

 ourselves whether, for instance, geologists at some 

 future period will be able to prove that our different 

 breeds of cattle, sheep, horses, and dogs are descended 

 from a single stock or from several aboriginal stocks. 

 .... This could be effected by the future geologist 

 only by his discovering in a fossil state numerous 

 intermediate gradations ; and such success is im- 

 probable in the highest degree." 



It is irrational to demand a perfect gradational 

 series in any number. The actually preserved 

 record is well described as a "chapter of accidents." 

 We have no right to expect, in any particular case 

 we choose to select, that the chain shall be complete, 

 and the links all forthcoming on demand ; but we have 

 a right to expect some few well-marked examples of 

 transitional series of forms, and also that none of the 

 facts actually ascertained shall be inconsistent with 

 our theory. 



The Geological Evidences of Evolution. 



The second preliminary point concerns the nature 

 of fossils. Directly intermediate forms between two 

 existing genera must not be expected, and can 

 indeed very rarely have existed. The theory of 

 Evolution requires that distinct genera shall be 

 linked together, not by a direct connection, but by 

 the descent of both from a common ancestor. 



