16 VITAL ACTIONS. 



itself is nothing but a mass of roots formed by the 

 leaves and buds. 



32. The principal office of the root is to attract 

 food from the ground. For this purpose it is fur- 

 nished, as has been seen, with an extremely hygrome- 

 trical point, or spongelet, which is capable of absorb- 

 ing incessantly whatever matter of a suitable kind 

 may lie in its neighbourhood. Its force of absorption 

 is always proportioned to the quantity of food that a 

 plant requires : when the sap is consumed rapidly by 

 the leaves, as in the spring, the roots are in rapid 

 action also ; and as the summer advances, and the 

 leaves require a smaller quantity of food, the roots 

 become more and more torpid.. 



33. The proportion borne by the root to the stem 

 is very variable. In such plants as succulent Euphor- 

 bias, and probably in all plants whose perspiring 

 powers are feeble, the roots are much smaller than 

 the stem ; but, in others, the circle occupied by these 

 organs must be very much greater than that of the 

 branches. In young Oaks this is well known to be 

 the case, but the disproportion diminishes as such 

 plants advance in age. 



34. There is no period of the year when the roots 

 become altogether inactive, except when they are 

 actually frozen. At all other times, during the win- 

 ter, they are perpetually attracting food from the 

 earth, and conveying it into the interior of the plant, 

 where it, at the season, is stored up till it is required 

 by the young shoots of the succeeding year. The 



