156 ACTION OF THE SOIL ON PLANTS. 



ever, in taking it out of her hands, if we can produce the 

 effect more rapidly. The sand-hills, which are, in many 

 places, formed oh the sea-coast, owe their origin to sand 

 thrown up by the high tide, and which, abandoned by the 

 receding waters, dries, and is carried by the wind farther 

 inland, and out of the reach of successive tides. The 

 sand-hills formed in the vicinity of Bourdeaux formerly 

 threatened the destruction of the adjacent country : it 

 was calculated that no less than seventeen villages would 

 be overwhelmed by them in the course of a century ; when 

 M. Bremontier was so fortunate as to discover a means 

 of averting this danger. Observing that sand thus thrown 

 up was not devoid of moisture, he scattered over it the 

 seeds of broom and of maritime pine ; and, in order to 

 prevent their being swept away by the wind, he covered 

 them with brambles and branches of underwood. The seed 

 sprouted; the broom first rose above ground, and some 

 time after the young pines appeared : the latter, however, 

 made but little progress, seeming to be choked by the rapid 

 growth of the broom ; yet in the course of a few years the 

 pines gained the ascendency, and drove their antagonists 

 from the field ; or rather, I should say, like true cannibals, 

 after destroying the enemy, they fed upon their jemains. 



In the course of time it became necessary to thin this 

 vigorous forest of pines ; and their branches served to 

 shelter the seed scattered on neighboring sand-hills. 



Caroline. I recollect reading in Withering, that the 

 Arundo arenaria, or sea-matweed, which grows only on 

 the very driest sand on the sea-shore, prevents the wind 

 from dispersing the sand over the adjoining fields. The 

 Dutch have very probably known and profited by this fact. 



Mrs. B. Hitherto we have directed our attention 

 rather to the formation of new soils than to the improve- 

 ment of old ones : yet the latter is the point of most im- 

 portance in agriculture ; for we are much more frequent- 

 ly called upon to ameliorate the land already under til- 

 lage than to prepare a soil, on land which has not yet 

 yielded any produce. 



Soils may be improved by a variety of different pro- 



859. How are sand hills on the sea coast formed 1 860. What 

 is said of those in the vicinity of Bourdeaux 1 861. By what means 

 was the danger averted 1 862. What is of more importance than the 

 formation of new soils'? 



