26 BOOTS ABSORB AT ALL SEASONS. 



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 

 autumn advances, and leaves require a smaller quantity of 

 food, the roots become more and more torpid. 



The proportion borne by the root to the stem is very variable- 

 In such plants as succulent Euphorbias, 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. 



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 winter, they are perpetually attract- 

 ing food from the earth, and conveying it into the interior of 

 the plant, where, at that season, it is stored up tUl it is required 

 by the young shoots of the succeeding year. The whole tissue 

 of a plant will therefore become distended with fluid food by 

 the return of spring, and the degree of distension will be in 

 proportion to the mildness and length of the previous winter. 

 As the new shoots of spring are vigorous or feeble in propor- 

 tion to the quantity of food that may be prepared for them, it 

 follows, that the longer the period of rest from growth, the 

 more vigorous the vegetation of a plant will become when 

 once renewed, if that period is not excessively protracted. 



A critic remarks that, of the contitiually-absorbiiig power of the 

 roots, the simile of a wick of a candle is certainly one of the most 

 appropriate. The wick (as well as the spongioles of the root) by its 

 hygrometric quality continually conducts fluids to the flame, only the 

 spongioles, being continually renewed by their constant formatioij 

 onwards, are permanent. Others doubt whether any winter absorption 

 occurs, a fact however familiar to practical observers, and proved by such 

 examples as those quoted at pages 50 to 52. 



Powerful as the absorbing action of roots is found to be 

 those organs have Httle or no power of selecting their food • but 

 appear, in most cases, to take up whatever is presented to them 



