nt
principles by different men, etc., I am much surprised at the uniformity
of the result, and I am satisfied that there must be truth in the rule
that the small genera vary less than the large. What do you think?
Hypothetically I can conjecture how the Labiatae might fail--namely, if
some small divisions of the Order were now coming into importance in the
world and varying much and making species. This makes me want to
know whether you could divide the Labiatae into a few great natural
divisions, and then I would tabulate them separately as sub-orders. I
see Lindley makes so many divisions that there would not be enough in
each for an average. I send the table of the Labiatae for the chance
of your being able to do this for me. You might draw oblique lines
including and separating both large and small genera. I have also
divided all the species into two equal masses, and my rule holds good
for all the species in a mass in the six volumes; but it fails
in several (four) large Orders--viz. Labiatae, Scrophulariaceae,
Acanthaceae, and Proteaceae. But, then, when the species are divided
into two almost exactly equal divisions, the divisions with large genera
are so very few: for instance, in Solanaceae, Solanum balances all
others. In Labiatae seven gigantic genera balance all others (viz. 113),
and in Proteaceae five genera balance all others. Now, according to
my hypothetical notions, I am far from supposing that all genera go on
increasing forever, and therefore I am not surprised at this result,
when the division is so made that only a very few genera are on one
side. But, according to my notions, the sections or sub-genera of the
gigantic genera ought to obey my rule (i.e., supposing a gigantic genus
had come to its maximum, whatever increase was still going on ought to
be going on in the larger sub-genera). Do you think that the sections
of the gigantic genera in D.C. Prodromus are generally NATURAL: i.e.
not founded on mere artificial characters? If you think that they are
generally made as natural as they can be, then I should like very
much to tabulate the sub-genera, considering them for the time as good
genera. In this case, and if you do not think me unreasonable to ask it,
I should be very glad of the loan of Volumes X., XI., XII., and
XIV., which include Acanthaceae, Scrophulariaceae, Labiatae, and
Proteaceae,--that is, the orders which, when divided quite equally, do
not accord with my rule, and in which a ve