Variation, Geographical Distribution, and Succession. 97 



mutual resemblance, as we suppose, he includes them in that 

 species. This will be more apparent should the discovery of the 

 transitions which he leads us to expect hereafter cause the four 

 provisional species which attend Q. robur to be merged in that 

 species. It may rightly be replied, that this conclusion would 

 be arrived at from the likeness step by step in the series of 

 forms ; but the cause of the likeness here is obvious. And this 

 brings in our " motif philosophique." 



Not to insist that the likeness is, after all, the variable, not 

 the constant element, — to learn which is the essential thing 

 (resemblance among the individuals, or their genetic connexion), 

 we have only to ask which can be the cause of the other. 



In hermaphrodite plants (the normal case), and even as the 

 question is ingeniously put by DeCandolle in the above extract, 

 the former surely cannot be the cause of the latter, though it 

 may, in case of crossing, offer occasion. But, on the ground 

 of the most fundamental of all things in the constitution of 

 plants and animals, the fact, incapable of further analysis, 

 that individuals reproduce their like, that characteristics are 

 inheritable*, the likeness is a direct natural consequence of the 

 genetic succession ; and it is logical to place the cause above the 

 effect. 



We are equally disposed to combat a proposition of DeCan- 

 dolle^s about genera, elaborately argued in the ' Geographic 

 Botanique,' and incidentally reaffirmed in his present article, 

 viz. that genera are more natural than species, and are more 

 correctly distinguished by people in general, as is shown by 

 vernacular names. But we have no space left in which to pre- 

 sent some evidence to the contrary. 



Here we must abruptly close our long exposition of a paper 

 whicli, from the scientific position, ability, and impartiality of 

 its author, is likely at this time to produce a marked impression. 

 We would also direct attention to an earlier article in the same 

 important periodical (viz. in the Bibl. Univ. for May 1862), on 

 the European Flora and the Configuration of Continents in the 

 Tertiary Epoch, a most interesting abstract of, and commentary 

 on, the introductory part of Heer^s ' Flora Tertiaria Helvetiae,' 

 as re-edited and translated into French by Gaudin, with additions 

 by the author. 



* See Sillinian's Journal, ser. 2. vol, xxix. (March 1860) p. 166, for the 

 enunciation of this obvious principle. 



Ann. 6f Mag. N. Hist. Ser. 3. Vol. xii. 



