114 THE METHOD OF DARWIN. 



reasonable by pointing out analogies between 

 the gemmules and the reproductive elements, 

 between their affinities and those of pollen, 

 etc. ; and rebutted the objection of excessive 

 minuteness by a comparison with molecules. 

 Doubtless the gemmules were a development 

 of the idea of reproductive elements, or blood- 

 corpuscles, or both ; and their peculiar origin, 

 powers, and hypothetical history were deter- 

 mined by the various facts that had to be 

 explained. It was a clear case of pure induc- 

 tion, untainted by any direct or indirect evi- 

 dence of the existence of the gemmules, or any 

 glimpse of the process by which characters are 

 transmitted. Darwin knew how speculative 

 the hypothesis was, and justified it because it 

 brought all the facts of inheritance together 

 under one point of view. 



In his discussion of it he first stated the 

 facts to be brought together, and then the 

 hypothesis with a working explanation of it, 

 and finally tried to show, by reasoning deduc- 

 tively from the hypothesis to the facts in which 

 it had originated, that it explained them. 



Usually during the effort to reach a cause by 

 the road of induction the cause itself is caught 

 sight of, either directly or indirectly, and it is 

 then possible to formulate at once at least a 



