LECTURE II. 



the roots of bulbous plants, but also on other thick root-fibres. It is clear that, 

 from the place where a root-fibre has closely applied itself to the soil by means of 

 its root-hairs, this shortening of the older tract of fibre must tend forcibly to 

 draw its point of attachment back to the mother root, or to the part of the stem 



Fu: 



-IG. 14 



A wheat plant during g-emiination. Fig. 14 four weeks older than Fig. 13. .S the seed (or, properly, the fruit) ; /> first 

 leaf; W^W^ apices of roots not yet covered with root-hairs; ee in Fig. 13 parts of root the hairs of which are attached to 

 particles of soil— in Fig. 14 these portions (f) are older and the root-hairs have perished— younger parts [e' €') have own 

 become attached to the soil. 



whence it rises. A vertical tap-root will thus be drawn tight in various 

 directions b}^ its numerous side rootlets, very much as the mast of a ship 

 is strained and made fast in different directions by the cordage. This ten- 

 sion, ari.sing from subsequent shortening, shows itself especially in the aerial 



