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 



