ced with
the two colours blended together." In the second case related by Mr.
Trail, about sixty blue and white potatoes were cut in halves through
the eyes or buds, and the halves were then joined, the other buds being
destroyed. Union took place, and some of the united tubers produced
white, others blue, while some produced tubers partly white and partly
blue.

=Adhesion of the axes of plants belonging to different species is a=
more singular occurrence than the former, and is of some interest as
connected with the operation of grafting. As a general rule
horticulturists are of opinion, and their opinion is borne out by facts,
that the operation of grafting, to be successful, must be practised on
plants of close botanical affinity. On the other hand, it is equally
true that some plants very closely allied cannot be propagated in this
manner. Contact between the younger growing tissues is essential to
successful grafting as practised by the gardener, and is probably quite
as necessary in those cases where the process takes place naturally.
Although there is little doubt but that some of the recorded instances
of natural or artificial grafting of plants of distant botanical
affinities are untrustworthy, yet the instances of adhesion between
widely different plants are too numerous and too well attested to allow
of doubt. Moreover, when parasitical plants are considered, such as the
Orobanches, the Cuscutas, and specially the mistleto (_Viscum_), which
may be found growing on plants of very varied botanical relationship,
the occurrence of occasional adhesion between plants of distant affinity
is not so much to be wondered at. Union between the haulms of wheat and
rye, and other grasses, has been recorded[60]. Moquin-Tandon[61] relates
a case wherein, by accident, a branch of a species of _Sophora_ passed
through the fork, made by two diverging branches of an elder
(_Sambucus_), growing in the Jardin des Plantes of Toulouse. The branch
of the _Sophora_ contracted a firm adhesion to the elder, and what is
remarkable is that, although the latter has much softer wood than the
former, yet the branch of the harder wooded tree was flattened, as if
subjected to great pressure[62]. It is possible that some of the cases
similar to those spoken of by Columella, Virgil[63], and other classical
writers, may have originated in the accidental admission of seeds into
the crevices of trees; in time the seeds grew, and as they did so, the