ow whether, say, the isolation of parts, that are usually combined
together, is congenital (_i.e._ the result of an arrest of growth
preventing their union), or whether it be due to a separation of parts
primitively undivided; the effect remains the same, though the cause may
have been very different.

The principal alterations to be mentioned under this head may therefore
be conveniently arranged under the following categories:--Union,
Independence, Displacement, Prolification, Heterotaxy, and Heterogamy.

PART I.

UNION OF ORGANS.

The union of parts, usually separate in their adult condition, is of
very common occurrence as a malformation. The instances of its
manifestation admit of being grouped under the heads of Cohesion, where
parts of the same whorl, or of the same organ, are united together; and
of Adhesion, where the union takes place between members of different
whorls, or between two or more ordinarily wholly detached and distinct
parts. In either case, the apparent union may be congenital (that is,
the result of a primitive integrity or a lack of separation), or it may
really consist in a coalition of parts originally distinct and separate.
In practice it is not always easy to distinguish between these two
different conditions. Indeed, in most cases it cannot be done without
tracing the development of the flower throughout all its stages. It is
needless to make more than a passing allusion to the frequency with
which both congenital integrity or subsequent coalescence of organs
exist under ordinary circumstances. Considered as a teratological
phenomenon, union admits of being grouped into several subdivisions,
such as Cohesion, Adhesion, Synanthy, Syncarpy, Synophty, &c. Each of
these subdivisions will be separately treated, but it maybe here said
that, in all or any case, the degree of fusion may be very slight, or it
may be so perfect that there may be a complete amalgamation of two or
more parts, while to all outward appearance the organ may be single.
The column of Orchids may be referred to as an illustration under
natural circumstances of the complete union of many usually distinct
parts.

In the uncertainty that exists in many cases as to the real nature of
the occurrence, it would be idle to attempt to explain the causes of
fusions. It is clear, however, that an arrest of development will tend
towards the maintenance of primordial integrity (congenital fusion), and
that pressure will i