My dear Sir

I am much obliged for your letter of Sep 2^nd explaining to me about the vines. I should expect that the Madresfield vine was originally a sport of the Hamburgh & reverted to it after being in-arched.¹ The case is very curious, but does not immediately concern me.

I have not received the spec^ns. of berries which you intended to send me, but this is now of no importance. I have never heard of yr observations of roots secreting carbonic acid; but Prof: Sachs has proved this by growing plants in polished marbe pots.² I return Sir J. Herschel’s letter; yr observation on the coincidence of the pulse & step are quite new to me.³

Dear Sir | Yrs faithfully | Ch. Darwin