DR MISTLETOES AND LORANTHUSES. 
is, presently, solid resisting wood. The root being no longer able to split the tissue 
with its point, is stopped in its growth at this spot. But there is nothing to pre- 
vent its continuing to grow along a course somewhat nearer the periphery, and 
outside the limit of the new annual ring of solid wood, where a fresh development 
of soft and tender cells has taken place in the cambium, and this indeed actually 
happens. 
Thus, every addition to the length of the Loranthus-root, as it grows onward 
between the wood and the cortex of the oak-branch, is further removed from the 
axis of the branch; or, in other words, the surface of contact between root and 
wood has the conformation of a flight of stairs, of which the lowest step constitutes 
the base, and the uppermost the apex of the root (see fig. 481). These steps are 
very small, their height varying from about 5 mm. to 7 mm., but they may be 
distinguished quite clearly in longitudinal sections, on account of the darker colour 
of these roots contrasting with the lighter oak-wood. Nutritive fluids are imbibed 
by the Loranthus-root from the wood of the oak at the surface of contact, and it 
is probable that this absorption takes place especially at the notches forming the 
steps. The root can only elongate, naturally, during the period when there is a 
young and fragile cell-layer superimposed upon the solid wood, whence it follows 
that in Loranthus the continuation of the root’s growth is more dependent upon a 
particular season and upon the annual progress of development of the host than is 
the case with the Mistletoe. There may be some connection between this cireum- 
stance and the fact that the Mistletoe possesses evergreen leaves, whilst Loranthus 
is green only in summer, acquiring fresh green foliage in the spring in the very 
same week as the oak does, and casting its leaves in the autumn simultaneously 
with the tree it infests. 
The stem which issues from the embryo of a Loranthus-seed grows away from 
the oak-branch into the open air, and develops with great rapidity at the expense 
of the nutriment absorbed from the host’s wood, and conveyed to it by the root 
above described, into a dense, dichotomously-branched bush. In summer it is not 
unlike a Mistletoe-bush, but in autumn, when it has cast its leaves, it acquires a 
totally different aspect owing to the dark-brown branches and the conspicuous 
yellow clusters of berries. 
Bushes of Loranthus grow to a greater size even than those of the Mistletoe; 
their stems attain not infrequently a thickness of 4 em., and clothe themselves with 
a blackish, rugged bark, the older stems of this kind being then usually studded by 
an abundance of lichens. At the spots where stems of Loranthus spring from an 
oak-branch they are always surrounded by a great rampart of wood belonging to 
the oak, and the base of the stem is often fixed in a deep symmetrically-rounded 
bowl reminding one vividly of the similar structures out of which the stems of 
Balanophorex arise. But whereas in Balanophoree this bowl-shaped rampart 
appertains to the parasite, in Loranthus it is formed from the wood of the host- 
plant, ze. the oak. It must, in the case we are considering, be interpreted as an 
exuberant growth of wood-cells and compared to the hypertrophies called galls, 
