

PARASITIC PLANTS. 183 



of the Mistletoe on the Oak is extremely rare, so 

 that it is said to have been regarded by the Druids 

 as a sacred event, and to have formed part of their 

 religious rites. 



The seedling has two cotyledons which are 

 imbedded in albumen. In germination the por- 

 tion of the caulicle under the cotyledons elongates, 

 and grows towards the bark of the tree, exactly as 

 the caulicle of an ordinary seedling grows towards 

 the ground. When it reaches the bark it makes 

 a disk, and, out of the middle of this disk, a fine 

 root-fibre enters the bark of the tree, and pene- 

 trates it as far as the wood. 



The following year the tree forms a new ring 

 of wood, which surrounds the root-fibre of the 

 Mistletoe and pushes out the bark before it. The 

 root does not grow into the wood, but the wood 

 grows around the root, so that it would in course 

 of time be completely buried up. To prevent this, 

 a zone of cells is formed around the base of the 

 Mistletoe root, which keeps pace in its growth 

 with the ring of w r ood, and apparently continues 

 outward the growth of the root. This growing 

 zone of cells sends out side branches which run 

 parallel with the axis of the branch and incorpo- 

 rate themselves with the bark. These branches 



