90 PLANT LIFE 



structure and indeed the whole conformation 

 of the plant is dominated by the leaf or other 

 equivalent green surface 



CHAPTER IX 



MECHANICAL PROBLEMS AND THEIR SOLUTIONS 



WE will, in the first place, direct our atten- 

 tion to the mechanical problems which affect 

 plants. These are, broadly speaking, the 

 same as those which confront the engineer 

 in his ordinary work of building and con- 

 struction. There are a variety of stresses 

 and strains that have to be guarded against, 

 unless the fabric is to collapse either by its 

 own weight or by the action of other external 

 forces. These mechanical requirements are 

 satisfied in practice by choosing materials 

 which, in the first place, possess the requisite 

 physical characters of strength, toughness 

 and the like ; and in the second, by utilising 

 them to the best mechanical advantage 

 economy is combined with efficiency. 



Now it may safely be said that in the 



