193 
Species and other Controversial Points. 
of some geological change — -it will make a difference in the spread of a given 
set of species about a given area. Mr. Ridley demands geological 
catastrophes, but apparently (p. 557) even the glacial period is not 
sufficient. 
No one who is unaccustomed to the handling of statistics of large 
numbers can perhaps easily realize how unassailable my figures actually are. 
If we move up one half of every class, we still get rarity figures of 3-8, 3*0, 
and 2-6. One must not arbitrarily move up endemics without moving up 
wides, and the figures cannot be equalized unless all are placed in the VC 
class, which is an obvious impossibility under Natural Selection, and on my 
hypothesis could not in any case occur unless the appearance of new species 
(wide or endemic) were stopped, and perhaps 60,000 further years allowed, 
as indicated in a valuable paper by Mr. Ridley (2). 
The figures given will suffice to show the weakness of Mr. Ridley’s 
attack upon my position. To quote exceptions, as he does, makes no 
difference. He need not have searched the world for them, but might have 
found them by the dozen in Trimen’s Flora. Probably in about a third of. 
the cases the actual figure there given does not represent the real truth, but 
that does not invalidate the argument, which simply goes to show that 
the overwhelming factor in distribution is age, though many other factors 
are continually at work. Pulling this way and that, however, and not acting 
upon whole groups of allied forms in the same way, their effects do not 
show in the figures. 
Mr. Ridley quotes about seventy cases in various connexions. Many 
of these, e. g. those on p. 555, are excellent illustrations of what I have said 
(6) on p. 22, that a very small accident may kill out a species in the class 
VR. In others he sets out to show that VC species may easily disappear, 
but only shows that they have disappeared in particidar localities . But for 
the sake of argument let us accept all these cases as showing each that one 
of my wides is five classes too high. Then instead of 4,579 marks for the 
1,508, we get 4,929 (i. e. by adding 350), and a rarity of 3-2 instead of 3-0. 
Or, to make the case as strong as possible, let us omit all the VC species, 
which Mr. Ridley thinks are introduced, and divide the seventy into two, 
one half moving the wides down as much as possible, the other the 
endemics up. Even then, a little calculation will show that the rarities come 
out (in figures 1 to /) 3*2, 2*7, and 2-4. My arguments could be carried 
on from these figures just as effectively as from those that were actually 
used. 
Unless Mr. Ridley can produce large numbers of cases which all move 
the wides down and the endemics up, it is idle waste of time to bring up 
exceptions. But the case no longer rests upon estimates ; these have been 
replaced by actual measurements in the case of New Zealand, and Mr. Ridley 
would have to show that 902 endemics, but no wides, were each under- 
