864 THE MISTLETOE IN HEREFORDSHIRE. 
relation to the wood of the nourishing plant, in the cambial layer of 
which the point rests, and there ceases to grow. In its passage 
towards the wood, it gives off several horizontal or side roots, which 
run along the branch in the bark, or upon the surface of the wood. 
These side-roots give origin to perpendicular suckers, which come into 
contact, like the original root, with the surface of the wood. The 
wood and bark of the mother-plant, in their periodical increase, form 
layers around the suckers, which grow in exactly the same manner in 
the cambial stratum, (Pitra,) and thus the hardened suckers come to be 
embedded in the body of the wood.” Dr. Harley goes on to state, 
amongst other particulars, that their perpendicular roots are tapering, 
diminishing in size from the circumference towards the centre; that 
there are usually three or four, and sometimes five or six of such per- 
pendicular roots; that their terminations are always composed of deli- 
eate tubular cells joined end to end, and arranged parallel to each 
other and to the long axis of the root, and that these roots are always 
arranged strictly parallel to the medullary rays of the nourishing plant. 
“ The young cellular root of Viscum may be regarded generally as a pro- 
longation of the central pith of the parasite, and contiguous medullary 
rays of the nourishing plant are successively confluent with it3 surface.” 
Having minutely described the loose porous structure of the stem 
and base of the Mistletoe, Dr. Harley says, “with regard to the 
direction and arrangement of the roots of the Viscum which lie within 
the wood, this is determined by the arrangement of the medullary 
system of the nourishing plant, the roots always lying strictly parallel 
to the medullary rays; " a conclusion to which he was led by the fact, 
that the Mistletoe and the supporting branch grow at right angles to 
each other, and that on a transverse section the Mistletoe-roots are 
shown to be arranged like the radii of a circle from the circumference 
towards the central pith. 
“The horizontal ramifications (side roots) of the base have plainly 
the same structure as the young perpendicular roots. | Whichever 
direction they take, they produce, at frequent and pretty regular in- 
tervals, other tapering cellular roots, which, guided doubtless by the 
medullary rays of the bark, press towards the surface of the wood, and 
are thus brought in contact with the ends of its medullary rays. They 
are subsequently found embedded at various depths in the hard wood 
of the nourishing plant, like the primary roots. These lateral roots 
