Ill LECTURES ON EVOLUTION 89 



than what it was, the bones would have been 

 dissolved, the layers of sandstone would have 

 fallen together into one mass, and not the 

 slightest indication that the animal had existed 

 would have been discoverable. 



I know of no more striking evidence than these 

 facts afford, of the caution which should be used 

 in drawing the conclusion, from the absence of 

 organic remains in a deposit, that animals or 

 plants did not exist at the time it was formed. I 

 believe that, with a right understanding of the 

 doctrine of evolution on the one hand, and a just 

 estimation of the importance of the imperfection 

 of the geological record on the other, all difficulty 

 is removed from the kind of evidence to which I 

 have adverted ; and that we are justified in 

 believing that all such cases are examples of what 

 I have designated negative or indifferent evidence 

 that is to say, they in no way directly advance 

 the hypothesis of evolution, but they are not to be 

 regarded as obstacles in the way of our belief in 

 that doctrine. 



I now pass on to the consideration of those 

 cases which, for reasons which I will point out to 

 you by and by, are not to be regarded as demon- 

 strative of the truth of evolution, but which are 

 such as must exist if evolution be true, and which 

 therefore are, upon the whole, evidence in favour 

 of the doctrine. If the doctrine of evolution be 

 true, it follows, that, however diverse the different 



