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82 PLANT EEMAINS IN NORTH AMERICA.
extensive, known to have an abhorrence of self-fertilization. It may
not be out of place to hazard a reason for this course
There would seem to be two distinct principles in relation to form
going along together with the life of a species. The tendency of the
one force is to preserve the existing form ; the other to modify, and
extend it to newer channels. The first we represent by the term in-
heritaijce, the other we understand as variation. Inheritance struggles
to have the plant fertilize itself with its own pollen ; whilst the eiForts
of variation are towards an intermixture of races or even neighbouring
individuals, rather than with members of the one brood or family.
May it not be possible that at some time in their past history all spe-
cies of plants have been hermaphrodite ? that Dioecism is a later triumph
of variation, its final victory in the struggle with inheritance ?
There are some difficulties in the way of sucli a theory, as there are
with most of these theories ; but it seems clear from this case of Epigeea
that cultivation has not as much to do with changes as it gets credit
for, and we may readily believe that, independently of external circum-
stances, there is a period of youth and a period of old age in form as
well as in substance, and that we may therefore look for a continual
creation of new forms by a process of vital development, just as ra-
tional)}' and as reverently as for the continued succession of new indi-
viduals.
The discovery of dicecism in Epigaa is interesting from the fact that
it is probably the first instance known in true Ericacece. In the Eri-
cal suborder of Erancoacecr, abortive stamens are characteristic of the
family, and in the FyrohicucB antherless filaments have been recorded.
Meehans Gardtner^s Munilihj, February, 1869.
ON THE PLANT EEMAINS FOUND IN THE CRETACEOUS
AND TERTIARY STRATA OF NORTH AMERICA.
The Cretaceous flora of Britain, and indeed of Europe, presents an
assemblage of i)laiits very different from those which succeeded them
in the same area, either in Tertiary or recent times. The fruits of
Fandanett, arborescent Liliacea, several genera of Cycadece, species of
Jrancarin and Sequoia, with numerous Ferns and gigantic Eqidseta,
are found in the Cretaceous beds of Britain. M. Coemans has de-
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