APPKOACHING DARWIN'S VIEWS 447 



and a big one, C. nutans. I never heard of their being 

 supposed to be varieties by any one, and they differ in many 

 points ; but the Himal. specimens are all of an intermediate 

 form its small states identical with acanthoides, its large 

 with small nutans. These facts shake species to their 

 foundation but according to my view of species, as con- 

 trasted with other systematists, there are sore few of them. 

 In fact if there were a possibility of bringing your and my 

 opinions to book, it might prove that we were not so far 

 divided. The more I study the more vague my conception 

 of a species grows, and I have given up caring whether 

 they are all pups of one generic type or not that the main 

 forms remain so long distinct; that we may through their 

 characters trace their distribution, is certainly all we can 

 expect to prove in our day ; and the laws of that distribution 

 more than we shall establish in our life-time. 



I have a glorious fact for you. A tropical species of 

 Cyperus (polystachys) and a tropical Fern, Pteris longifolia, 

 grow in the hot soil of the Volcano of Ischia and nowhere 

 else in Europe or the Mediterranean : see Hooker's Journ. 

 Bot. for Nov. 1854, p. 351 (it is on Athenaeum table). Now 

 I can wriggle out of the Fern case by allowing ubiquitous 

 meteoric dispersion of Fern spores, but the Cyperus is a dis- 

 gusting and detestable fact that disgusts my soul within me. 

 I must however have a bite at you if I can, and so will ask 

 why if the Cyperus and Pteris got there no other migrants did ? 



March 2, 1855. 



I am going on with the Tasmanian Flora and find the 

 subject very interesting. Some of the scarcest and most 

 local Alpine plants reappear on the isolated summits of the 

 Australian Alps, and thence too I have the English Sagina 

 procumbens, which, as far as I know, has not been found 

 in the South Hemisphere, except in the Falklands (this 

 wants study though). I am also preparing as I go on for 

 a general work on Geogr. distrib. of the whole Australian 

 Flora this is ambitious, but it is really the most extra- 

 ordinary thing in the whole world. The Flora of Swan 

 Eiver, i.e. of extra tropical S.W. Australia, will I believ 

 turn out to be the most peculiar on the Globe and specifically 

 quite distinct from that of N.S. Wales also generically to a 

 much greater degree than any two similarly situated areas. 



