MISTLETOES AND LORANTHUSES. 207 
to stick with the radicle of the seedling pointing away trom the branch; the 
whole axis of the embryo curving towards the surface of the bark in a very striking 
manner. Thus the radicle always reaches the bark, and having done so it becomes 
adpressed and cemented to its surface, spreads itself out in the form of a doughy 
mass, and so develops into a regular attachment-dise. From its centre a slender pro- 
cess now grows into the bark of the host-plant, piercing the latter and penetrating 
as far as the wood, but not growing into that tissue. This penetrating process has 
been termed a “sinker”, and must be looked upon as a specially modified root. 
Fig. 47.—Bushes of Mistletoe upon the Black Poplar in winter. 
The development of the first year ends with the formation of this sinker. 
When the winter is over, the branch, into which the sinker is inserted so as just 
to reach the wood with its point, grows in thickness, a new layer of wood-cells 
a 
so-called annual ring—being superimposed upon the wood of the previous year. 
The increasing mass of wood first surrounds the tip of the sinker with wood-cells, 
then forms a rampart all round it, pushing the cortical tissue, wherein that organ 
has hitherto been wedged, in front of it in an outward direetion, and in this way 
the sinker is at length fixed deep within the woody cylinder. The process of 
inclosure by the wood-layers, as they are built up, may be compared to the gradual 
surrounding of a stake on the sea-shore by the rising tide; the lowermost extremity 
is first immersed and then higher and higher parts until the whole is enveloped. The 
