WEEDS. 219 



about them which is necessary to their being in a healthy and 

 vigorous state. For this reason they run up slender, and re- 

 main of a loose and spongy contexture, and bend down and 

 lodge by their own weight, unless the weeds happen to be so 

 strong as to hold ,them up. 5. Weeds, besides the general 

 evil of taking away the food of plants, rob the soil, particular- 

 ly of its moisture, and speedily reduce it to such a. dry state, 

 that neither weeds nor other plants can receive from it any 

 vegetable food, for want of that proportion of moisture which 

 is necessary to give it fluidity. Accordingly it is observable 

 that the abounding of weeds brings on an early appearance of 

 drought ; and some weeds of the creeping kind twine about 

 the plants in such a manner as to prevent their growth, and the 

 circulation of their sap. Others shade them, and shut out the 

 direct influence of the sun ; while others, the dodder in partic- 

 ular, it is believed, draw their nourishment directly out of the 

 bodies of plants, by sticking their fibres into them, and thereby 

 cause them to decline. 



So many and great are the mischiefs done by weeds, that 

 when they are suffered to grow unmolested among useful 

 plants, whatever culture may have been bestowed to prepare 

 a crop, is, in a great measure lost, and the seeds wasted. 



With a view to investigating the best means of subduing, 

 or destroying weeds, we should consider them as divided into, 

 two classes ; those which chiefly infest lands that are in til- 

 lage, and those that prevail in our grass land ; and how to 

 prevent the existence or prevalence of thera. 



When it is necessary to make use of new dung, or such a^ 

 may cofttain the seeds of weeds, it should be applied to hoed 

 crops, in preference to others, in the tilling of which, the 

 weeds will be destroyed as fast as they rise during the summer. 

 But it is best to avoid carrying seeds on to other tillage lands 

 when practicable, while they retain their germinating princi- 

 ple. No dung or compost manure should therefore be applied 

 ^o the soil, until it has undergone such fermentation i n heaps, 



