BY C. C. BRITTLEBANK. 653 



The radicle, having reached the branch, becomes rapidly 

 enlarged, spreading out into a hemispherical mass, which is formed 

 of two flounce-like layers, one within the other. As the plant 

 matures, branches arise from the outer layer, which thus takes 

 the place of the bole or trunk of ordinary plants. The inner 

 portion, or attachment disc, becomes at first firmly cemented, and 

 in time grafted to the host (PI. xx., figs.2-3). If the attachment- 

 disc be removed after being in contact with the branch for a 

 period of from ten to twenty days, it will be found to be some- 

 what concave, and have a cleft running three-fourths across the 

 upper surface (Pl.xv., fig. 28). This cleft is formed by the sides 

 of the disc, which are parallel to, and in contact with the branch, 

 and which thicken and meet in the centre, forming a small 

 chamber in the upper portion of the disc. 



From the upper surface of this chamber a wedge-shaped process 

 grows downward, corresponding to the sinker of Loranthus 

 Europceus. This wedge passes through and is held in position by 

 the lips of the cleft, which is always parallel to the longer axis 

 of the branch (Pl.xvii., fig. 2; Pl.xv., fig. 29). Growth proceeding, 

 the sinker passes through the bark, enters the sapwood, and if 

 the branch be slender, passes completely through, appearing on 

 lower side, where it becomes covered by its own bark. After 

 passing the centre of the branch the invading process gradually 

 increases in width, making a dove-tailed joint (Pl.xvi., figs.2-3V 

 Or, the process having penetrated the bark, sapwood and that of 

 the previous year's growth, invades the annular rings, and then 

 splits the branch along the medullary rays, which it also invades, 

 thus uniting the inner and outer layers of parasitic growth (Plates 

 xvi.,fig.l, xvii.,fig.l,xviii., tig. 4). In other instances the process, 

 after penetrating to the centre of the branch, invades nearly all 

 the medullary rays. Owing to the withdrawal of sap the branch 

 beyond the parasite is retarded in growth, dies, and falls away. 

 In this case the base of the parasite overgrows the entire end of 

 the branch, which directly below the junction is much swollen 

 and somewhat trumpet-shaped, the hemispherical base of the 

 parasite making a junction more or less at right angles to the 



