844 THE ORIGIN OF SPECIES 



iuorganic substances, or the falling of a facetted spheroid 

 from one facet to another, hardly deserve consideration. 

 One class of facts, however, namely, the sudden appear- 

 ance of new and distinct forms of life in our geological 

 formations, supports at first sight the belief in abrupt 

 development. But the value of this evidence depends 

 entirely on the perfection of the geological record, in 

 relation to periods remote in the history of the world. 

 If the record is as fragmentary as many geologists stren- 

 uously assert, there is nothing strange in new forms 

 appearing as if suddenly developed. 



Unless we admit transformations as prodigious as 

 those advocated by Mr. Mivart, such as the sudden 

 development of the wings of birds or bats, or the sud- 

 den conversion of a Hipparion into a horse, hardly any 

 light is thrown by the belief in abrupt modifications on 

 the deficiency of connecting links in our geological for- 

 mations. But against the belief in such abrupt changes 

 embryology enters a strong protest. It is notorious that 

 the wings of birds and bats, and the legs of horses or 

 other quadrupeds, are indistinguishable at an early em- 

 bryonic period, and that they become differentiated by 

 insensibly fine steps. Embryological resemblances of all 

 kinds can be accounted for, as we shall hereafter see, 

 by the progenitors of our existing species having varied 

 after early youth, and having transmitted their newly 

 acquired characters to their offspring, at a correspond- 

 ing age. The embryo is thus left almost unaffected, and 

 serves as a record of the past condition of the species. 

 Hence it is that existing species during the early stages 

 of their development so often resemble ancient and ex 

 tinct forms belonging to the same class. On this view lit 



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