DIFFERENT FORMS OF STEMS. 107 



in many others, as the Sugar-cane and other Canes, we observe 

 certain divisions of the stem, which are called nodes or knots. 

 Where the remainder of the stem is hollow, it is always solid 

 here ; and the partition has a peculiar degree of firmness, derived 

 from the interlacing of fibres from all sides : and where the 

 remainder of the stem is filled up (as in the Sugar-cane) with soft 

 spongy tissue, there is still the same kind of firm division at the 

 node. The space between the node is termed the internode ; 

 and from each one of these divisions, we usually find a single 

 leaf-bud, or pair of leaf-buds, originating. The division into 

 nodes is not so perceptible in Exogens ; but it may be regarded 

 as always existing. It is best seen in the young shoots of the 

 Vine; where the fact that, from each internode but a single bud 

 or pair of buds originates, is equally evident. Hence, when the 

 stem itself does not exhibit any distinct division by nodes, the 

 Botanist is accustomed to regard them as existing, near the points 

 from which leaves or branches arise; and to consider as inter- 

 nodes, the spaces between these. 



149. Many parts are commonly regarded as Roots, which 

 are in reality Steins. Their position, whether above ground, or 

 beneath the surface, is no criterion as to their real nature. It 

 has been seen (. 110) that roots sometimes grow in the air ; 

 and it is equally true that stems frequently grow in the earth. 

 What are ordinarily called bulbous roots, for example, such as 



FIG. 55 SECTIONS OP BULBS : A, Tulip ; B, Hyacinth : a, a, buds most advanced 

 b, b, buds less advanced ; c, base of the bulb 



