128 FLOWER-GARDENING. 



season, when the cellular tissues of two "different parts, or of 

 two different plants, are kept for some time in contact ; but as 

 none but tissues of nearly the same nature will adhere, grafting 

 and budding, which are caused by the adhesion of contiguous 

 parts, can only take place either between different varieties of 

 the same species, or between nearly related species ; and even 

 then only when the corresponding parts of the scion or bud 

 and the stock are placed in contact. 



20. Woody fibre conveys fluid in the direction of its length, 

 gives stiffness and flexibility to the general system, and acts as 

 a protection to spiral and other delicate vessels. 



21. Spiral vessels convey oxygenated air. 



22. Other vessels probably conduct fluid when young, and 

 air when old. 



23. As the bodies of which all tissue is composed are per- 

 fectly simple, unbranched, and regular in figure, having, when 

 elongated, their two extremities exactly alike, they are more or 

 less capable of conVeying gaseous matter or fluids in any direc- 

 tion, and, consequently, a current may be reversed in them 

 without inconvenience ; hence inverted cuttings or stems will 

 grow. 



[If cuttings will grow when the top ends are stuck in the 

 ground, I have never had the satisfaction of seeing them. I 

 have often heard that sprouts of trees and bushes will grow 

 with the top end down, but I have never met with a person 

 who has seen such a thing. S. EDWARDS TODD.] 



24. All parts of plants are composed of tissue, whether they 

 be soft, as pulp, or hard, as the bony lining of a peach. 



25. With regard to Horticultural operations, the parts of 

 plants should be considered under the heads of Root (II.) ; 

 Stem (III.) ; Leaf Buds (IV.) ; Leaves (V.) ; Flowers (VI.) , 

 Sexes (VII.) ; Fruit (VIII.) ; and Seed (IX.). 



