STRUCTURE OF ROOTS 37 



or more of each) ; the smallest and first-formed tissues of 

 the wood are to the outside, the later ones are well developed, 

 large, and in some species they meet and fill the centre of 

 the root with wood ; in others the middle is occupied by 

 a pith. 



The tissues of the root are of several kinds and modified 

 to serve special purposes ; the root-hairs absorb from the 

 soil water which is passed through the cortex to the wood, 

 and the latter conducts it upwards to the shoots. The 

 organic food, which, as we shall see later, is formed in the 

 leaves, is conducted by the bast and neighbouring delicate 

 tissues to the growing organs and storage-tissues. 



CHAPTER IV 

 WORK OF THE ROOT 



In our study of germinating seeds we found that the 

 root was the first organ to be formed, and that its appear- 

 ance was followed by the emergence of the young shoot. 

 What is the future of such a root ? How does it grow ? 

 Of what special use is it to the plant ? How does it do its 

 work ? A few experiments and observations will help us 

 to answer these questions. 



Direction of growth of root and shoot. In a pot of fibre 

 or soil, sow three soaked Bean seeds, one with the radicle 

 pointing downwards, another horizontally, and a third 

 upwards. After a few days examine them. In what 

 directions have the radicle and plumule grown in each ? 

 (Fig. 17, 1, 2, 3.) We observe that the radicle endeavours 

 to grow downwards into the dark, moist soil, independently 

 of the position in which the seed was placed in the ground, 



