80 Mr. Griffith on the Development of 



occasionally reciprocally united by "suckers;" in such there is actual com- 

 munication between the ligneous systems*. 



With respect to the parts on which the parasitism occurs, I believe it is 

 entirely dependent on the permanence of their nature. I have met with a 

 solitary instance of the attachment and evolution of Loranthus on the leaf of 

 a Guttiferous tree. The plant had reached the height of two inches, and had 

 developed several leaves ; no lateral shoot had been sent out. Its base was 

 expanded on the upper surface of the leaf, and the sucker-like root had pene- 

 trated the cuticle, and was firmly imbedded in the parenchymatous mesophyl- 

 lum. Although in all probability this plant would, had it been left to its own 

 fate, have perished, yet it might have become, before this had taken] place, 

 attached by a lateral shoot to a part capable of sustaining it by its permanent 

 nature. I am also of opinion that attachment will take place on any plantf, 

 or part of a plant, the duration of which is sufficiently long. Those with 

 milky juice, though perhaps a general, are not an universal exception. 



I have met with a species flourishing on the Artocarpus integrifolia. The 

 juice of this species was not milky; it is hence obvious that they have an 

 eliminating power, although the fact stated by De CandoUe J of coloured fluids 

 passing into their tissue through the stock would lead us to suppose other- 

 wise. 



With respect to the bourrelets formed round each attachment, they are 

 occasioned by the deposit of new wood round their bases ; they are often 

 irregular, the upper part being, as might be expected, somewhat more de- 

 veloped. 



I have never seen any secondary roots sent off" either into the interior of the 

 wood, or between the bark and wood§. 



* It will be interesting to compare this with grafts, on which subject I am quite ignorant. I think 

 the attachment of Loranthus is not analogous to grafts. 



t I have seen seeds of Loranthus germinating on the succulent fronds of a Polypodium. 



X Physiologic V^getale, vol. ii. p. 790; and vol. iii. p. 1411. 



§ I have before mentioned that in one species of Viscum both primary and secondary external at- 

 tachments take place. A slight examination of another species, in which no lateral shoot had been 

 developed, leads me to suspect that the mode of adhesion of Viscum album is not thoroughly under- 

 stood ; and that the appearance of roots running between the bark and wood of the stock is, perhaps, 

 attributable to a peculiar modification of the wood of the latter. Whatever the cause may be with 



