THE STEM, OK ASCENDING AXIS. 



33 



sisting of young wood bearing one or more buds. These " strike" root 

 when planted in the earth. So the grape-vine and hop. 



159. The Offset is a term applied to short side-branches ending in 

 a tuft (rosette) of leaves, and capable of taking root when separated 

 from the parent plant, as in houseleek. 



41, A strawberry plant (Fragaria vesca) sending out a runner. 



160. The Runner is a prostrate, filiform branch issuing from certain 

 short-stemmed herbs, extending itself along the surface of the ground, 

 striking root at its end without being buried. Thence leaves arise and 

 a new plant, which in turn sends out new runners ; as in the strawberry. 



161. The node or joint of the stem marks a definite point of a pecu- 

 liar organization where the leaf with its axillary bud arises. The nodes 

 occur at regular intervals, and the spaces between them are termed in- 

 temodes. This provides for the symmetrical arrangement of the leaves 

 and branches of the stem. In the root no such provision is made, and 

 the branches have no manner of arrangement. 



162. Why the stem gradually diminishes upwards. In the in- 

 ternodes the fibres composing the stem are parallel, but at the nodes 

 this order is interrupted in consequence of some of the inner fibres 

 from below turning outwards into the leafstalk, causing more or less a 

 jointed appearance. Hence each internode contains fewer fibres than 

 those below it. 



163. How the stem grows. The growth of the stem consists in 

 the development of the internodes. In the bud the nodes are closely 

 crowded together, with no perceptible internodes, thus bringing the ru- 

 dimentary leaves in close contact with each other. But in the stem, 

 which is afterwards evolved from that bud, we see full grown leaves 

 separated by considerable spaces. That is, while leaves are developed 

 from the rudiments, internodes are evolved from the growing point. 



164. But there are exceptions here as to all other rules in science, adding 

 another element of diversity to the endless gradation of form in Nature's works. In 



