FOLIAGE OF TREES AND PLANTS. 65 



by a tree when we view its foliage, each leaf being 

 employed in receiving and transmitting gases from 

 the air in certain proportions to the plant : these 

 great operations having been effected during the 

 summer months, and this agency of the leaves 

 finished, they fall to the ground, not as an useless 

 incumbrance, but to convey a large portion of fresh 

 soil peculiarly fitted for the nutriment of vegeta- 

 tion. Should they remain in any quantity beneath 

 the tree, they appear to be injurious to the smaller 

 herbage, but they are more generally dispersed as 

 they part from the sprays by the gales of autumn, 

 which whirl them along in crowds to the hedges, 

 trenches, and ditches around : here they accumulate 

 and decay, furnishing, in conjunction with other 

 vegetable decompositions, a very nutritive earth, 

 as is manifest by the wild plants growing in those 

 situations, for notwithstanding all the obstructions 

 of shade, thorns, and briers, they are generally 

 found in great luxuriance or health. This earth in 

 time crumbled by frosts, and washed by rains into 

 the ditches from the banks, becomes accumulated 

 there, and we collect it, compost it with other 

 matters, and use it as a beneficial dressing for our 

 cultivated lands : many of these leaves, however, 

 remain near the tree, and soon communicate their 

 virtues to the herbage : some are consumed by 

 natural consequences, others are attacked by small 

 fungi, which break their surfaces, admit moisture, 



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