ical
peas,--all three kinds would be ranked as indisputably distinct
species.

Andrew Knight[600] has observed that the varieties of peas keep very
true, because they are not crossed by insects. As far as the fact of
keeping true is concerned, I hear from Mr. Masters of Canterbury, well
known as the originator of several new kinds, that certain varieties
have remained constant for a considerable time,--for instance,
_Knight's Blue Dwarf_, which came out about the year 1820.[601] But the
greater number of varieties have a singularly short existence: thus
Loudon remarks[602] that "sorts which were highly approved in 1821, are
now, in 1833, nowhere to be found;" and on comparing the lists of 1833
with those of 1855, I find that nearly all the varieties have changed.
Mr. Masters informs me that the nature of the soil causes some
varieties to lose their character. As with other plants, certain
varieties can be propagated truly, whilst others show a determined
tendency to vary; thus two peas differing in shape, one round and the
other wrinkled, were found by Mr. Masters within the same pod, but the
plants raised from the wrinkled kind always evinced a strong tendency
to produce round peas. Mr. Masters also raised from a plant of another
variety four distinct sub-varieties, which bore blue and round, white
and round, blue and wrinkled, and white and wrinkled peas; and although
he sowed these four varieties separately during several successive
years, each kind always reproduced all four kinds mixed together!

With respect to the varieties not naturally intercrossing, I have
ascertained that the pea, which in this respect differs from some other
Leguminosae, is perfectly fertile without the aid of insects. Yet I have
seen humble-bees whilst sucking the nectar depress the keel-petals, and
become so thickly dusted with pollen, that some could hardly fail to be
left on the stigma of the next flower which was visited. I have made
inquiries from several great raisers of seed-peas, and I find that but
few sow them separately; the majority take no precaution; and it is
certain, as I have myself found, that true seed may be saved during at
least several generations from distinct varieties growing close
together.[603] Under these circumstances, Mr. Fitch raised, as he
informs me, one variety for twen