422 GROWTH OF THE 'ORIGIN.' [1855 



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 intro- 

 duced 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 ascer- 

 tained 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 transport al. 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 pro- 

 portion of the Umbelliferae are xf-J-g = ^ ; 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 dis- 

 tant 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 'propor- 

 tional 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 intro- 

 duced Compositae in Great Britain to all the introduced 

 plants, and the result was, ^f = 9% . In our aboriginal or 

 indigenous flora the proportion is T V; and in many other 

 cases I found an equally striking correspondence I then 

 took your Manual, and worked out the same question ; here 

 I find in the Compositae an almost equally striking correspond- 

 ence, viz / 4 6 1 m tne introduced plants, and -fff-^ i i r 



