266 APPENDIX. 



" To a correct appreciation of the results obtained from the 

 above table, it may be remarked, that the organic matter of 

 the soil (sometimes called gcine) — the food of plants — the 

 substance, wliich, by the action of air and water, has been 

 prepared, or is in course of preparation, to enter into the 

 circulation of the plant, — is that portion of the soil which 

 chiefly communicates to it its prolific qualities ; and that, all 

 other things being equal, a soil may be expected to be pro- 

 ductive, in proportion to the amount of oi'ganic matter it 

 contains.* 



" Tins organic matter is in part soluble, and in part inso- 

 luble, in alkali. The soluble portion of it is supposed, with 

 much plausibility, to be that which is already prepared to 

 become nutriment for plants ; the insoluble portion is 

 regarded as that which, by the action of air and moisture, 

 and other influences, will hereafter become so. 



" If this theory be an accurate one, it follows that those 

 soils which contain a large proportion of soluble organic 

 matter will be fertile for the time ; but that they must also 

 contain a good supply of insoluble geine to preserve their 

 fertility. And thus the column of soluble organic matter in 

 the table is that which measures the present productiveness, 

 and that of insoluble organic matter th^t which indicates the 

 durability of the soil. 



" The salts which enter into the composition of a soil are 

 considered by agricultural chemists as its stimulating ingi'c- 

 dient. Chaptal, in his ^ Chemistry applied to Agriculture,' 

 says (a little fancifully, perhaps), ' The salts are to plants, 

 what spices and marine salts are to man.'t It is certain that 



" * An exception to this rule, which should not be overlooked, exists in 

 the case of bog or peat soils ; which, however, possess in general but little 

 soluble organic matter." 



*' t Dr. Dana improves on this idea. He says : ' The earths are the 

 plates, the salts the seasoning, and the geine the food of plants.' " 



/ 



