As to the “Manual,” my plan, as at present advised, is to cross the line of slavery a little, to take in Kentucky and Virginia; this makes the real division, in botanical geography, between North and South. It should be Northern ground, too, down to this line: for north of it slave labor is good for nothing; and there would be no slaves there, except for the Southern market. I cannot take in Missouri, for I must make the Mississippi my boundary. But all your St. Louis plants cross into Illinois, do they not? Tell me how this is. I shall get at work at the new edition soon. I shall first press on the “Lessons” a little further. About Fouquiera; I have examined it here repeatedly on the live plant, which every year prolongs its main axis an inch or two. And I took leaves to Providence to show there, especially to remove any lingering doubt on Torrey’s mind. For Torrey would long have it that the spine was a primary leaf, and that an axillary leaf adhered to it by its petiole. He now knows better. I just saw Agassiz. He looks well and strong.... I read Alphonse De Candolle’s “Géographie Botanique Raisonnée” on the voyage home: a most able work it is, full of interesting matter very methodically arranged. Hooker and Thomson’s “Flora Indica,” vol. i., is famous for its able introductory essay, etc. TO A. DE CANDOLLE. October 27, 1855. Your welcome letter of the 7th of August duly reached me. I meant to have surprised you by an answer dated at Paris; but the eleven days I passed there were too busily occupied to allow it. M. Boissier will have told you of my sudden voyage, and the cause of it. I was absent from home only six weeks and a day; and twenty-two days of the forty-three were passed on the water. On returning home I found here: 1. The excellent lithographed portrait of yourself, a pleasing and pretty good likeness. Of the three copies I have offered one to Torrey, the other to Short. 2. The copy of “Géographie Botanique,” which you so kindly addressed to me. (I have already learned that Agassiz and Darlington have theirs; but Torrey not his, and I have directed inquiries to be made.) This was not my first introduction to the book; for I bought a copy of Masson in Paris, to read on the voyage, when I could have more leisure than at home. And I carefully read it then (after having dispatched Hooker and Thomson’s “Flora Indica”) up as far as to p. 1087, when I was obliged by the close of the voyage to break off, at a very interesting point; and I cannot yet resume the reading. I cannot sufficiently express my profound admiration of this book, so thorough and conscientious, so capital in its method, and embodying such a vast amount of facts well discussed; it might well be the work of a long life. I have marked in many places points on which I may have a word to say, sometimes little details to add or correct, sometimes a criticism to hazard.