I found, when actually
making the list, that I could never strike a balance in my mind,--a good
many varieties occurring together, in small or in large genera, always
threw me off the balance...

P.S.--I have just thought that your remark about the much variation of
monotypic genera was to show me that even in these, the smallest genera,
there was much variability. If this be so, then do not answer; and I
will so understand it.

LETTER 62. TO J.D. HOOKER. February 23rd [1858].

Will you think of some of the largest genera with which you are well
acquainted, and then suppose 4/5 of the species utterly destroyed and
unknown in the sections (as it were) as much as possible in the centre
of such great genera. Then would the remaining 1/5 of the species,
forming a few sections, be, according to the general practice of average
good Botanists, ranked as distinct genera? Of course they would in that
case be closely related genera. The question, in fact, is, are all the
species in a gigantic genus kept together in that genus, because they
are really so very closely similar as to be inseparable? or is it
because no chasms or boundaries can be drawn separating the many
species? The question might have been put for Orders.

LETTER 63. TO J.D. HOOKER. Down, February 9th [1858].

I should be very much obliged for your opinion on the enclosed. You may
remember in the three first volumes tabulated, all orders went right
except Labiatae. By the way, if by any extraordinary chance you have
not thrown away the scrap of paper with former results, I wish you would
return it, for I have lost my copy, and I shall have all the division
to do again; but DO NOT hunt for it, for in any case I should have gone
over the calculation again.

Now I have done the three other volumes. You will see that all species
in the six volumes together go right, and likewise all orders in the
three last volumes, except Verbenaceae. Is not Verbenaceae very closely
allied to Labiatae? If so, one would think that it was not mere chance,
this coincidence. The species in Labiatae and Verbenaceae together
are between 1/5 and 1/6 of all the species (15,645), which I have now
tabulated.

Now, bearing in mind the many local Floras which I have tabulated
(belting the whole northern hemisphere), and considering that they (and
authors of D.C. Prodromus) would probably take different degrees of care
in recording varieties, and the genera would be divided on differe