information. I am so very glad that you think of drawing up some notice on your geographical distribution, for the air of the Manual strikes me as in some points better adapted for comparison with Europe than that of the whole of North America. You ask me to state definitely some of the points on which I much wish for information; but I really hardly can, for they are so vague; and I rather wish to see what results will come out from comparisons, than have as yet defined objects. I presume that, like other botanists, you would give, for your area, the proportion (leaving out introduced plants) to the whole of the great leading families: this is one point I had intended (and, indeed, have done roughly) to tabulate from your book, but of course I could have done it only VERY IMPERFECTLY. I should also, of course, have ascertained the proportion, to the whole Flora, of the European plants (leaving out introduced) AND OF THE SEPARATE GREAT FAMILIES, in order to speculate on means of transportal. By the way, I ventured to send a few days ago a copy of the "Gardeners' Chronicle" with a short report by me of some trifling experiments which I have been trying on the power of seeds to withstand sea water. I do not know whether it has struck you, but it has me, that it would be advisable for botanists to give in WHOLE NUMBERS, as well as in the lowest fraction, the proportional numbers of the families, thus I make out from your Manual that of the INDIGENOUS plants the proportion of the Umbelliferae are 36/1798 = 1/49; for, without one knows the WHOLE numbers, one cannot judge how really close the numbers of the plants of the same family are in two distant countries; but very likely you may think this superfluous. Mentioning these proportional numbers, I may give you an instance of the sort of points, and how vague and futile they often are, which I ATTEMPT to work out...; reflecting on R. Brown's and Hooker's remark, that near identity of proportional numbers of the great families in two countries, shows probably that they were once continuously united, I thought I would calculate the proportions of, for instance, the INTRODUCED Compositae in Great Britain to all the introduced
Table of Contents
CHAPTER 1.XI. — THE GROWTH OF THE 'ORIGIN OF SPECIES.'
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