56 NEW PUBLICATIONS. 
compiler, always astonishes beginners. There are many plants placed 
in it in the first degree of commonness, which I have never seen, 
though I have walked about much in very varied parts of Britain, 
But it may be thought that though the results of numerical compari- 
sons are not in detail absolutely correct, yet that the broad features 
must be true by the aid of the general doctrine of averages. Yet very 
often these results are absolutely false in their broadest features ; and 
mainly for two reasons, which I will illustrate by two cases." 
It would quadruple the length of our quotation if we reprinted his 
two cases, supposed to be illustrations. Suffice it to say, that they are 
wholly irrelevant, arising from the author's own mistake in not distin- 
guishing between numerical summaries and floral comparisons, — be- 
tween the sums total of many local lists added together and the species- 
differences between two of them placed in comparison, one with the 
other. The given problem is, how most nearly to ascertain the com- 
parative frequency of species, those which most successfully or least 
successfully hold their places in the struggle for existence, under actual 
present conditions. The method adopted in the ■ Cybele Britannica ' 
is to consider the whole surface of Britain apportioned into 38 dis- 
tricts, and these again subdivided into 112 minor sections. Those 
species which have been ascertained to occur seemingly wild in all the 
38 districts are taken to form the first class of generality, and then to 
rank in commonness among themselves according to the number of the 
112 sections in which they are also known to occur. Hereafter it may 
become possible to apply a more rigorous test, while we much doubt 
that any more precise measure could be practically carried out at the 
present day. 
That the results of such a method should "astonish beginners " is 
likely enough, because beginners usually form a rude and empirical 
estimate of frequency from very local observation, or very brief expe- 
rience. It might reasonably be expected also that such results would 
not exactly accord with the personal experience of Mr. C. B. Clarke, 
or even with the individual experience of any other single botanist. 
But if a good botanist truly could " walk about much in very varied 
parts of Britain " and yet fail to find " many of the plants placed in 
the first degree of commonness," this sort of experience would well 
warrant much distrust of the method, and might even justify a declara- 
tion that the results so obtained " are absolutely false in their broadest 
features." 
