ird set the
nucleus was included within the tegument, the ovules having in all
respects their natural external conformation, containing, however, not
only pollen-grains, but also a layer of those peculiar spheroidal cells,
including a fibrous deposit, which are among the normal constituents of
the anther. In one case, where the coat of the ovule was imperfect, and
allowed the nucleus to protrude, the pollen was evidently contained
within the central mass of the structure. In this instance the fibrous
cells were not detected, these being only found in cases where the
investment of the ovule was perfect; and hence it seems likely that the
fibrous cells were part of the coat of the ovule, while the pollen was
formed within the nucleus. In no case was any trace of embryo sac to be
seen.

The main interest, as Mr. Salter remarks, in these cases is
physiological; so far as structure alone is concerned, there does not
appear any reason why pollen-grains should not be developed in any
portion of the plant; the mother cells in which the pollen is formed not
differing, to all outward appearance, from any other cells, unless it be
in size.

The fundamental unity of construction in all the organs of plants could
hardly be better illustrated than by these cases; while, in spite of
their exceptional nature, they must be of great interest
physiologically, as showing the wide limits of possible variation which
thus may even involve the sex, "for an ovule to develop pollen within
its interior," says Mr. Salter, "is equivalent to an ovum in an animal
being converted into a capsule of spermatozoa. It is a conversion of
germ into sperm, the most complete violation of individuality and unity
of sex. * * * * The occurrence of an antheroid ovule and a normal ovule
on the same carpellary leaf realises the simplest and the most absolute
form of hermaphroditism."

It must, however, be remarked that the term substitution would be
preferable to conversion. There is, at present, no evidence to show that
the germinal vesicles were present in these cases; on the other hand, it
seems most probable that they were not, so that the presence of the
pollen-cells must be considered as simply adventitious. It can hardly be
that they were, in the first instance, germinal vesicles, which, in
course of time, became so modified as to assume the appearance of
pollen-grains. Between the nucleus of the ovule and the tubercle of
cellular tissue constituting the