XI PHENOMENA OF ORGANIC NATURE 453 



causes of the Present and of the Past conditions of 

 ORGANIC NATURE, 



Such is the hypothesis as I understand it. Now 

 let us see how it will stand the various tests which 

 I laid down just now. In the first place, do these 

 supposed causes of the phenomena exist in nature ? 

 Is it the fact that, in nature, these properties of 

 organic matter atavism and variability and 

 those phenomena which we have called the con 

 ditions of existence, is it true that they exist ? 

 Well, of course, if they do not exist, all that I have 

 told you in the last three or four lectures must be 

 incorrect, because I have been attempting to prove 

 that they do exist, and I take it that there is 

 abundant evidence that they do exist ; so far, 

 therefore, the hypothesis does not break down. 



But in the next place comes a much more diffi 

 cult inquiry : Are the causes indicated compe 

 tent to give rise to the phenomena of organic 

 nature ? I suspect that this is indubitable to a 

 certain extent. It is demonstrable, I think, as I 

 have endeavoured to show you, that they are per 

 fectly competent to give rise to all the phenomena 

 which are exhibited by RACES in nature. Further 

 more, I believe that they are quite competent to 

 account for all that we may call purely structural 

 phenomena which are exhibited by SPECIES in 

 nature. On that point also I have already en 

 larged somewhat. Again, I think that the causes 

 assumed are competent to account for most of the 



