67 



in the depth to which they enter — a conclusion which all who 

 have made careful sections of the bough with the Mistletoe 

 attached to it, wiU have no difficulty iu believing. It forms 

 another example of the common law in organic h£e, that when 

 two living structures impinge on each other in a confined space, 

 the one possessing the lowest power of vitality must give way 

 to the other, and here it is the dense wood of the tree that is 

 gradually caused to be absorbed by the pressure of the soft cellular 

 growth of the perpendicular roots of the Mistletoe. 



"When the roots of the Viscum Album" says De. Haelet 

 again, "have become fairly infixed into the medullary system of 

 nourishing plant, their outer portions become gradually thickened 

 by the formation of woody layers upon their surfaces. This in- 

 crease in the lateral dimensions of the root takes place, pari 

 passu, with that of the branch upon which it grows ; for every 

 layer of wood deposited on the branch, a corresponding one is 

 deposited upon the Mistletoe ; and the growth of the two plants 

 proceeding thus uniformly, the concentric rings of the stock pass 

 uninterruptedly into those of the Mistletoe, and the woody layers 

 become co-incident. "Whilst the roots thus undergo increase and 

 lignification about their outer portions, their inner extremities 

 which now lie deeply within the hard wood, constantly retain 

 their original soft cellular condition; they are in fact to the 

 viscum, what the cellular rootlets of terrestrial plants are to 

 them." 



