ignorant; we cannot even attribute them, as in the last class of cases, to
any proximate agency, such as relative position. I will give only a few
instances. It is so common to observe on the same plant, flowers
indifferently tetramerous, pentamerous, etc., that I need not give
examples; but as numerical variations are comparatively rare when the parts
are few, I may mention that, according to De Candolle, the flowers of
Papaver bracteatum offer either two sepals with four petals (which is the
common type with poppies), or three sepals with six petals. The manner in
which the petals are folded in the bud is in most groups a very constant
morphological character; but Professor Asa Gray states that with some
species of Mimulus, the aestivation is almost as frequently that of the
Rhinanthideae as of the Antirrhinideae, to which latter tribe the genus
belongs. Aug. St. Hilaire gives the following cases: the genus
Zanthoxylon belongs to a division of the Rutaceae with a single ovary, but
in some species flowers may be found on the same plant, and even in the
same panicle, with either one or two ovaries. In Helianthemum the capsule
has been described as unilocular or tri-locular; and in H. mutabile, "Une
lame PLUS OU MOINS LARGE, s'etend entre le pericarpe et le placenta." In
the flowers of Saponaria officinalis Dr. Masters has observed instances of
both marginal and free central placentation. Lastly, St. Hilaire found
towards the southern extreme of the range of Gomphia oleaeformis two forms
which he did not at first doubt were distinct species, but he subsequently
saw them growing on the same bush; and he then adds, "Voila donc dans un
meme individu des loges et un style qui se rattachent tantot a un axe
verticale et tantot a un gynobase."

We thus see that with plants many morphological changes may be attributed
to the laws of growth and the inter-action of parts, independently of
natural selection. But with respect to Nageli's doctrine of an innate
tendency towards perfection or progressive development, can it be said in