MISTLETOES AND LORANTHUSES. 



209 



The root-system of the Mistletoe taken as a whole may be described as like a 

 jaw-bone in shape, or, still better, a rake. The cross-beam of the rake corresponds 

 to the cortical root, whilst the teeth are analogous to the sinkers; the cross-piece 

 must be supposed to be parallel to the axis of the branch and lying under the bark, 

 and the spokes must be thought of as perpendicular to the axis and driven into the 

 wood. 



Whilst the roots of the Mistletoe-plant are spreading in the interior of the branch 

 in the manner described, the stem is developed outside. At the time when the 

 process, subsequently to be the first sinker, emerges from the attachment-disc of 



Fig. 48. — 1 Loranthus Buropwus, and 3 Mistletoe ( Viscum album)— boih parasitic ou branclies of trees, and seen in section. 

 ^ A piece of tlie wood of a Fir-tree perforated by tlie sinlters of a Mistletoe. 



the embryo and pierces through the bark, the cotyledons are still covered by the 

 white seed-coat, which rests upon them like a cap. But when once this first sinker 

 is firmly fixed and in a position to take up nutritive juices from the wood of the 

 host, the seed-coat is thrown ofi^; the apex of the stem, which is still very short, is 

 raised; the cotyledons are detached, whilst close above them is produced a pair of 

 green leaves. Thenceforward the development of the visible portion of the Mistletoe- 

 plant outside the bark keeps pace with that of the roots underneath the cortex, and 

 is moreover dependent upon the quantity of food taken up by the sinkers from the 

 wood. Where there is an abundant supply of nutriment, as in the case of poplars, 

 the growth of the Mistletoe is correspondingly exuberant; where the flow of juices 

 is scarce, the parasite is stunted in its growth, and often develops only small 

 yellowish sickly-looking tufts. If the foster-plant is of a lavish nature, adven- 



VOL. I. 14 



