1876 PANGENESIS 51 



From C. Darwin, Esq., to G. J. Romanes. 



Dear Romanes, As you are interested in Pan- 

 genesis, and will some day, I hope, convert an ' airy 

 nothing ' into a substantial theory, therefore I send 

 by this post an essay by Hackel, attacking 'Pan.,' 

 and substituting a molecular hypothesis. If I under- 

 stand his views rightly, he would say that with a bird 

 which strengthened its wings by use, the formative 

 protoplasm of the strengthened parts becomes changed, 

 and its molecular vibrations consequently changed, 

 and that their vibrations are transmitted throughout 

 the whole frame of the bird. How he explains rever- 

 sion to a remote ancestor I know not. Perhaps I have 

 misunderstood him, though I have skimmed the whole 

 with some care. He lays much stress on inheritance 

 being a form of unconscious memory, but how far this 

 is part of his molecular vibration I do not understand. 

 His views make nothing clearer to me, but this may 

 be my fault. No one, I presume, would doubt about 

 molecular movements of some kind. His essay is 

 clever and striking. If you read it (but you must not 

 on my account), I should much like to hear your 

 judgment, and you can return it at any time. 



We have come here for rest for me, which I much 

 needed, and shall remain here for about ten days more, 

 and then home to work, which is my sole pleasure in 

 life. I hope your splendid Medusae work and your 

 experiments on Pan. are going on well. I heard 

 from my son Frank yesterday that he was feverish 

 with a cold, and could not dine with the Physiologists, 



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