FLOWER-GARDENING. 127 



the soft and brittle" parts of plants, such as pith, pulp, the 

 spaces between the veins of leaves, and the principal part of 

 the petals. 



8. Succulent plants are such as have an excessive develop- 

 ment of cellular tissue. 



9. It may be considered the most essential kind of tissue, 

 because, while no plants exist without it, many are composed 

 of nothing else. 



10. Tissue is called Woody Fibre when it is composed of 

 slender tubes, which are conical and closed at each end, and 

 placed side by side. 



11. Woody fibre is what causes stiffness and tenacity in 

 certain parts of plants ; hence it is found in the veins of leaves, 

 and in bark, and it constitutes the principal part of the wood. 



12. Vascular Tissue is that in which either an elastic tough 

 thread is generated spirally within a tube that is closed and 

 conical at each end ; or rows of cylindrical cellules, placed end 

 to end, finally become continuous tubes by the loss of their 

 ends. 



13. The most remarkable form of vascular tissue is the 

 Spiral Vessel, which has the power of rolling with elasticity 

 when stretched. 



14. Other kinds of vascular tissue are incapable of unrolling, 

 but break when stretched. 



15. Spiral vessels are not found in the wood or bark, and 

 rarely in the roots of plants. 



16. Vascular tissue of other kinds is confined to the root, 

 stem, veins of leaves, petals, and other parts composed of leaves. 

 It is not found in bark. 



17. The common office of the tissue is to convey fluid or 

 air, and to act as the receptacle of secretions. 



18. Cellular tissue conveys fluids in all directions, absorbs 

 with great rapidity, is the first cause of the adhesions that 

 take place between contiguous parts, and is the principal 

 receptacle of secreted matter. 



19. Adhesion will take place at all times during the growing 



