PROCEEDINGS OF THE SOOIETY. 93 
to the interior of the plant. ‘‘In this respect they appear to bear some 
analogy to the medullary rays, which are supposed to convey air from the 
bark to the young wood, and they may be the very organs by which the 
medullary rays communicate with the atmosphere. They might, with great 
propriety, be called mesophla@ic bands.” The second point to which atten- 
tion was directed, was the relationship between a graft or a bud, and the 
stock upon which it is worked. Although the graft grows by means of the 
sap supplied to it through the stock, and though the stock increases in size 
by the deposition of wood from the graft, the stock and the graft each retain 
their specific character, even to the minutest particular of colour, size, form, 
and qualities. Several instances which were apparently exceptions to this 
rule were cited, the chief of which was Cytisus Adami, This, which is evi- 
dently a hybrid between C. Laburnwm and C. purpureus, is usually propa- 
gated by grafting on the former. It has dingy red flowers, but very 
frequently reverts by bud-yariation to its own parents, and bears, intermixed 
amongst its own branches, others which produce the flowers and leaves of 
C. Laburnum, and some which produce the flowers and leaves of C. purpureus. 
. . . . So far this strange plant appears to afford only a very fine 
example of bud-variation, but let us enquire how the hybrid was produced. 
In the first place, all attempts have failed to produce, by artificial impreg- 
nation, a hybrid between C, Labwrnum and C. purpureus. But in a bed of 
seedling Laburnums which were grown in a garden where C. purpureus also 
grew, there were some veritable hybrids; so that it seems that in a state of . 
nature it is possible for an occasional hybrid to occur between the two species, 
But the account given by M. Adam himself of the origin of the hybrid is 
very different and highly curious. He had grafted a bud of C. purpureus 
into a stock of C, Laburnum. This bud remained dormant the first year, 
but the year after sent up a great many branches, one of which grew much 
more luxuriantly than the rest. Now, this robust branch was propagated 
before it had flowered, and the young plants were sold for C. purpureus, 
which it was only rational to expect they would be; but when they came 
to flower, they turned out to be hybrids. Here, then, is a case in which the 
stock seems to haye affected the graft in a most remarkable manner. But 
the probable explanation of the phenomenon is, that a bud of the purpureus 
graft united in some way with a bud of Zaburnum stock, which happened to 
touch it; and that the hybrid was formed by the union of buds, and not 
from any influence the stock exercised upon the graft.’? After glancing at 
parasites in connexion with this subject, Mr. Holland spoke of the theory of 
morphology, and adduced many illustrations in support of it; these in- 
cluding instances, not merely of reversion, but of the conyersion of certain 
parts of plants into the more complex organs, The paper, which was very 
Taterestilig, was lictetied te throughoiit with great attention, The Presidetit 
