viii Preface. 



framed upon either side of it. And, in the second 

 place, the question was not raised by Weismann. It 

 appears, indeed, from what he says, that he never 

 caught a glimpse of it till about ten years ago, and 

 that he then did so as a result of his own independent 

 thought. Moreover, it is perfectly true that to him 

 belongs the great merit of having been the first to 

 call general attention to the subject, and so to arouse 

 a world-wide interest with reference to it. But to 

 suppose that the question was first propounded by 

 Weismann is merely to display a want of acquaint- 

 ance with the course of Darwinian thought in this 

 country. As far back as 1874 I had long conversa- 

 tions with Darwin himself upon the matter, and under 

 his guidance performed what I suppose are the only 

 systematic experiments which have ever been under- 

 taken with regard to it. These occupied more than 

 five years of almost exclusive devotion ; but, as 

 they all proved failures, they were never published. 

 Therefore I here mention them merely for the pur- 

 pose of showing that the idea of what is now called 

 a " continuity of germ-plasm " was present to Dar- 

 win's mind as a logically possible alternative to the 

 one which he adopted in his theory of pangenesis — an 

 alternative, therefore, which he was anxious to ex- 

 clude by way of experimental disproof. If it be said 

 that no one could have been aware of this in the absence 

 of publication, I reply that I think it may be perceived 

 by any one who reads attentively his chapter on 

 Pangenesis. Moreover, early in the seventies his 



