346 IMPOSSIBLE GRAFTS. 



indispensable condition in grafting is a great similarity of the 

 stock and scion ; they must not only be nearly allied botanically, 

 but be much alike in the composition of their sap." 



To this effect writes Mohl in that admirable treatise of his 

 on the cells of plants,* the best work on Vegetable Physiology 

 ia any language. And this shows philosophically why it is 

 that the operations of grafting and budding cannot be performed 

 indifferently between any two species, although such was 

 formerly a general belief, it being even asserted that Eoses 

 became black when grafted on Black Currants, and Oranges 

 crimson if worked on the Pomegranate.^ In reality such 

 operations are successful in those cases only where the stock 

 and scion are very nearly allied ; and the degree of success is 

 in proportion to the degree of affinity or constitutional resem- 

 blance. Thus, varieties of the same species unite the most 

 freely, then species of the same genus, then genera of the same 

 natural order; beyond which the power does not extend, 

 unless, in the case of parasites like the Mistletoe, which grow 

 indifferently upon totally different plants. 1 . For instance. Pears 

 work freely upon Pears, very well on Quinces, less willingly on 

 Apples or Thorns, and not at aU upon Plums or Cherries ; 

 the Cherry will take on the Laurel, or mc© versa ; the Lilac on 

 the Ash, the Olive on the Phillyrea, the two last cases occurring 

 among plants of the same natural order. De CandoUe even 

 says that he has succeeded, notwithstanding the great difference 

 in their vegetation, in working the Lilac on the Phillyrea, the 

 Olive on the Ash, and Bignonia radicans on the Catalpa ; but 

 plants so obtained are very short-lived. For some curious 

 particulars upon this subject, see Physiologie VigetaUy 

 p. 788., &c.' 



* Prinoiples of the Anatomy and Physiology of the Vegetable Cell ; translated by 

 Henfrey. 8vo. Van Voorst. 1852. 



+ Et steriles platani maJos gessSre, yalentes 

 Castanese fagos, omusque incanuit albo 

 Flore pyri, glandemque sues fregdre sub ulmis. 



Georg. lib. ii. 

 X Grafting the Mistletoe should be performed about the middle of May. The Apple 

 or the Crab ia the best stoek, but it has succeeded on Balsam-Poplar, WiUow, and 

 many other trees. Mr. Beaton has succeeded in even working it on the Oak. 



