BOOK II. 



THE PHYSIOLOGY OF PLANTS. 



CHAPTER I. 



ABSORPTION. 



It is to the root and leaf that nature has intrusted the 

 great source of nourishment, absorption. 



The leaves imbibe moisture by the whole of their surface, 

 by every pore, whilst it is only by their fine hair-like fibres 

 that roots take up water from the soil. And still further, 

 in the root absorption is absolutely restricted as to extent ; 

 it does not take place through the whole of the capillary 

 filaments, but only by the microscopic spongiole which ter- 

 minates each of them, and acts the part of a sucker. Hence 

 Linnaeus compared the roots to the chyliferous vessels of 

 animals. 



The great roots of vegetables, to which the vulgar natu- 

 rally attribute the principal function of life, have really 

 nothing to do with it. A very simple experiment proves 

 this. If we place the body of the root of a plant in dry 

 sand, whilst the fine ends of the roots are in suitable soil or 

 in water, it continues to grow, displaying the freshest fo- 

 liage. But if, on the contrary, the main mass of the root 



