LOCAL FLOKAS AND VAEIETIES 457 



of the species being uniformly treated, because local Floras 

 consist of : 1. Local plants — ^these we agree are not so 

 variable as mundane plants. 



2. Mundane plants, of which only one form is found in 

 the said local area, and which are hence not treated as 

 variable in the Flora of that area. 



3. Mundane plants, of which two or more varieties are 

 found in the area. 



Now as you increase your area the small local (i.e. in- 

 variable) genera do not reappear, but the small mundane 

 genera do with an increased number of variations, and 

 the large mundane genera with their variable species also 

 relatively increase. Is this not so ? Be that as it may, 

 I have just got Weddell's monograph of Urticeae back 

 from binder, and as I told you that I thought it would 

 prove as unexceptional food for analysis as may be, I 

 have roughly tabulated the results and enclose them, 

 Weddell has reduced both the large and small genera 

 enormously and consistently, and I attach the greater 

 confidence to his work from the close accordance between 

 the relative number of species to variation in large and 

 small genera. 



Again, if the species of small local genera are themselves 

 local, it follows that we procure fewer specimens of the 

 species of such genera than of large, and hence make fewer 

 varieties. This any general Herbarium shows. A genus of 

 one species presents only a single specimen much oftener 

 than a genus of 10 species does only 10 specimens. 



Again, suppose I am naming by comparison or otherwise 

 a species of a large genus, I find it agrees a little with many 

 species, exactly with none, but most nearly one — I hesitate 

 and am in difficulty and my tendency is to make a var. of 

 that it is nearest, all the more if the latter is itself variable ; 

 but in naming in the same way a species of a small genus I 

 find no such difficulty — it is perhaps not exactly like the 

 species to which I refer it, still it is not the least like anything 

 else. So I made a var. of my first plant partly lest my 

 successor should refer it to any of the other species which 

 it resembled from missing it under the vars. of that I 

 refer it to, but in the second case no such precaution is 

 necessary. 



