154 DUTCH BULBS AND GARDENS 



of brown charred coal. In some parts bits of the wood have 

 been preserved whole and unchanged. 



In the Bailey of Amstelveen, near Amsterdam, bits of 

 wood are often disinterred which has still "heart" enough to 

 be used as ordinary wood. Between Alphen and Leyden are 

 to be found in several places whole tree trunks, ten or twelve 

 feet long. The derry matter is very substantial, and it is 

 very inflammable ; it also holds water, so that it does not run 

 through from the surface of the peat to the water in the soil 

 below it. In Zealand, where it is easily taken up, it is 

 forbidden under penalty of death x to carry away the peat, 

 because the water underneath, which it retains, would do 

 considerable damage in the island. 



As we now know that piles and blocks of wood can last 

 2000 years in the earth without rotting, so we may conclude 

 that these trees (which now compose the derry or turf) must 

 have been much longer undergoing the various operations 

 of nature which resulted in producing this change. No 

 tree roots can penetrate this derry, and wherever sand does 

 not cover it over a certain depth, no vegetation can grow. 

 Water falling on the peat is held there, having no means of 

 escape, and the sand on the top is, therefore, always moist 

 and fresh in proportion as it is near the derry. If one digs 

 a little hole in this ground, the water which " fattens " the 

 sand collects in a moment and fills up the hole which has 

 been made, and this becomes a running spring. These sort 

 of springs exist all over Holland, and they generally go by 

 the name of sand-wells. They are kept supplied only by 

 rain, or by the water which filters down through the sand 

 from the dunes, and this often to a great distance. 



If bulb roots were to reach down to within a foot of this 

 layer of peat they would be spoilt, and the bulbs would 

 perish. The depth of the sand-layer over the peat is 

 1 Two hundred years ago. 



