the Ovula of hovanthus and Viscnm. 81 



The influence these parasites possess over the stock is according to their 

 reciprocal size : L. Scurrula, generally attached to Melastoma malabathrica, 

 or other shrubs, frequently destroys them to a considerable extent. Others, 

 again, which are minute in comparison with the stock, such, for instance, as 

 those that grow upon trees, produce no appreciable deleterious effect. 



The foregoing notes apply chiefly to the development of the ovula. I had 



the generality of Loranthacea, with this species it is far different, the primary and secondary attach- 

 ments taking place by suckers which appear to reach the older formed wood. From the first attach- 

 ment roots are sent olF upwards and downwards. These run to a considerable length, and adhere 

 very firmly by means of suckers, which likewise are imbedded in the substance of the stem. 



In this specimen the branches are confined to the stem originating from the primary attachment. 

 The roots, however, have the power of sending off shoots. The suckers produce a most pernicious 

 effect on the branches along which the roots take their course, and from their large size soon produce 

 atrophy. 



These roots have the same anatomy as the branches, the medullary rays being less distinct and the 

 medulla almost obliterated ; it does exist, however, in a rudimentary state. 



The suckers are composed of cellular tissue, and form part of the cortical system, with which they 

 are continuous. The cells are long and arranged at right angles with the woody system. No cuticle 

 covers the adhering surface of the sucker. 



The pith is excentric, and, as might be expected, nearest the circumference on the side of the adhe- 

 sion. The more vigorous and older of these suckers pierce the albumen to a greater or less distance ; 

 but no identification of substance appears to take place, the fibres of the suckers being at right angles 

 with those of the alburnum. In all probability they have not the power of piercing into the substance 

 of the wood, their greater depth in the older and larger branches being owing to the deposit of new 

 ligneous matter. At the same time a corresponding increase takes place in the sucker, which becomes 

 hard towards its base. The upper bourrelet surrounding the suckers is always the larger. 



Tab. IX. fig. 1. represents a sketch taken from a sucker about three inches below the axis; irregu- 

 lar fascicles of woody matter have passed off from the wood into the sucker, into which they penetrate 

 deeply. They all appear to terminate at a short distance from the adhering surface of the sucker, 

 which is entirely cellular, and much less coloured than the rest ; it is still large. The terminations of 

 the woody fascicles are generally clavate. So great is this tendency to throw out suckers that when 

 two roots encounter each other, as they frequently do, they throw out suckers and form mutual adhe- 

 sions. In this case there is actual identification of structure, woody fibrous bundles passing off 

 from both and becoming identified with the wood. See Tab. IX. fig. 4. It does not take place through- 

 out the whole length of the sucker, but is chiefly confined to its upper position. 



Tab. IX. fig. 2. represents the original attachment on the apex of a branch. There is in this no 

 union between the woody systems, although the irregular woody bundles have at a, nearly reached 

 the pith. Still the edges of the wood of the stock are entire. The irregularities of this, observable 

 at b, c, depend probably upon an attempt at formation of wood on this side. The depth at which tlie 

 sucker has apparently pierced is owing in reality to its original attachment, which must have taken 

 place when the stem of the stock was very thin : consequently the pith would be near the surface. 



VOL. XVIII. M 



