CH. II.] THE ROOT. 61 



influence of the solar rays, they always vegetate 

 early, and ripen well their young wood, yet the quan- 

 tity of oxygen absorbed by the roots of annual plants 

 is very large, being, in the instances of the radish, 

 carrot, and others, not less than their own bulk in 

 the course of twenty-four hours. 



Digging, hoeing, and trenching are employed for 

 facilitating the access of the air to the roots of plants, 

 by rendering the texture of the soil easily perme- 

 able, and they are practices requiring a separate 

 consideration. 



Very few people ever consider in detail the 

 expenditui'e of labour required from the gardener 

 when digging. It is a labour above all others call- 

 ing into exercise the muscles of the human frame, 

 and how great is the amount of this exercise may 

 be estimated from the following facts : — 



In digging a square perch of ground in spits of 

 the usual dimensions, (seven inches by eight inches,) 

 the spade has to be thrust in 700 times, and as each 

 spadeful of earth, if the spade penetrates nine 

 inches, as it ought to do, ^rill weigh on the average 

 full seventeen pounds, eleven thousand nine hun 

 dred pounds of earth have to be lifted, and the 

 customar}' pay for doing this is S^tZ. ! 



As there are 160 perches or rods in an acre, in 

 digging the latter measure of ground, the garden 

 labourer has to cut out 112,000 spadefuls of earth, 



