CHAPTER XII. 



GEOLOGICAL FORMATIONS. 



THAT the geographical distribution of vegetables is greatly 

 affected by difference of soil in different localities is patent 

 to all ; and that these differences are attributable largely 

 to underlying geological formations may be readily ad- 

 mitted. 



There are plants, such as the lousewort, the butterwort, 

 and the marsh marigold, which we never find growing ex- 

 cepting on marshy spots ; there are others, such as the ling 

 and the heather, which we find only on what are known as 

 heath-lands, which consist largely of peat soil ; there are 

 others, such as the coltsfoot, found only on clay land ; 

 others like the oyster plant, only on sand ; and others, aa 

 are most of those with which we are conversant, are found 

 only on what is called garden soil. And agriculturists, 

 with all the appliances of modern science at their com- 

 mand, find it not only more profitable, but almost necessary, 

 if they would secure remuneration for their outlay of 

 money and labour, to confine themselves to the culture of 

 certain crops on light lands, and of others on heavy lands, 

 and it may be of others still on varieties of these as 

 numerous as the notes of the gamut. 



A carefully conducted analysis of any plant by burning, 

 and by a chemical analysis of the ashes, may be made to 

 show that there were in the plant besides carbon and 

 moisture, which may have been obtained in one way of 

 another from the atmosphere, mineral substances which 

 must have been obtained from the soil ; and an analysis of 

 the soil, made before the growth of the plant and after, 

 may be made to show that what the plant got the soil 



