72 LECTURES ON EVOLUTION in 



in correspondence with these alternations, we 

 observe the changes in the fauna and flora to 

 which I have referred. 



But the inspection of these changes give us 

 no right to believe that there has been any dis- 

 continuity in natural processes. There is no trace 

 of general cataclysms, of universal deluges, or 

 sudden destructions of a whole fauna or flora. 

 The appearances which were formerly interpreted 

 in that way have all been shown to be delusive, 

 as our knowledge has increased and as the blanks 

 which formerly appeared to exist between the 

 different formations have been filled up. That 

 there is no absolute break between formation and 

 formation, that there has been no sudden dis- 

 appearance of all the forms of life and replacement 

 of them by others, but that changes have gone 

 on slowly and gradually, that one type has died 

 out and another has taken its place, and that 

 thus, by insensible degrees, one fauna has been 

 replaced by another, are conclusions strengthened 

 by constantly increasing evidence. So that within 

 the whole of the immense period indicated by the 

 fossiliferous stratified rocks, there is assuredly not 

 the slightest proof of any break in the uniformity 

 of Nature's operations, no indication that events 

 have followed other than a clear and orderly 

 sequence. 



That, I say, is the natural and obvious teaching 

 of the circumstantial evidence contained in the 



