I am very glad you are turning your good, logical mind and immense knowledge to this class of topics; but do not let it run off with too much of your valuable time. I take far more satisfaction in discussing questions of botanical affinity; and long to get back to that sort of work. Just now, I must needs be absorbed in elementary work and teaching, but look to see an end of this. I have been watching the development of the ovules of Magnolia; nothing can be more normal than they are, in the early stages. When Wright comes home from Cuba I expect to get hold of his considerable north Japan collection, which I expect to find very interesting on questions of distribution, the very questions you ask me to consider. I doubt if our “mountain backbone” actually stops any species, itself, from advancing east or west. I wish you would compare our White Birch with the European B. alba, and let me know the result. Also the Chestnuts.... TO R. W. CHURCH. CAMBRIDGE, May 15, 1857. An acquaintance en route for Scotland has offered to take some small parcels for me. Among them is one I have taken the liberty to address to you, a copy of a very elementary book[36] I have prepared as an introduction to my favorite science, finding there was no one in use here which I thought fit to put into the hands of young beginners. Here botany is taught, somehow or other, in most schools, and generally by incompetent teachers from wretched books, i. e., those used in the ordinary schools and for young people. I have endeavored, in the little book I send you, to make real science as easy and simple as possible. I doubt if I have yet aimed low enough; but the book seems to take, and promises to be useful. Although not adapted for your meridian (where you have doubtless good elementary books enough), yet when your boy, who must now be five or six years old, if he has been spared to you, gets a few years older, I shall be much gratified if this little volume should interest him, and aid you somewhat in developing in his mind a love for the study of nature in one of its pleasantest branches.... I want to offer you my new “Manual of the Botany of the Northern United States,” not that it can be of any use or of much interest to you, but must not load my kind acquaintance with more parcels. I wait for an opportunity of sending through the booksellers, before long. TO JAMES D. DANA. November 7, 1857. If you have plenty, please send me two more copies of your “Thoughts on Species.” I first read it carefully, a week ago, and I meant to write you at once how I like it, and a few remarks, but something prevented at the time, and I have been very busy and preoccupied ever since.