46 Importance of correct Vegetable Analysis; [J^lyj 



plants. But whence come these wide discrepancies in the resuhs of 

 different investigators? Do they arise from imperfections in the 

 modes of analysis, or from actual variations in the composition of 

 the same species of plant when grown on different soils; or is it 

 owing to the analyses being made at different periods of the 

 growth of the plant? Doubtless all these causes have aided in 

 producing the result alluded to. But the perfection to which 

 chemical analysis is now carried should prevent the first from ex- 

 erting any influence in future. That the composition of the same 

 plant will vary to some extent, according to the composition of 

 the soil on which it is grown, or that one alkali may be made to 

 replace another in the living plant, within certain limits, is very 

 probable. But how far this variation may be carried, and yet 

 the plant be brought to full perfection, is a highly interesting 

 question for investigation. That the quantity of ash or inorganic 

 ingredients yielded by any given plant, at different periods of its 

 growth, varies considerably we already possess some positive evi- 

 dence. Thus De Saussure states that wheat straw, one month be- 

 fore flowering, yielded 7.9 per cent of ash; in flower, 5.4 per 

 cent; and when ripe with grain, only 3.3 per cent; and maize or 

 Indian corn presented a still greater variation. It is very possi- 

 ble that some of the discrepancies in the statements of different 

 writers concerning the composition of the same plant, may be 

 owing to this cause. And if so, it only proves the necessity of 

 accompanying every analysis with a full statement of the age 

 and condition of the plant analyzed; and also how easily valua- 

 ble facts are rendered useless and contradictory by the omission 

 of a single collateral circumstance. A well conducted series of 

 experiments for determining both the questions here alluded to is 

 demanded, as well by the practical bearing of the subject as by 

 the interests of science. Single or isolated facts in agriculture, 

 are only valuable when they are capable of being connected with 

 other facts in such a manner as to furnish general conclusions or 

 principles of action. Thus it is practically of no importance that 

 we know the single fact, that the composition of plants will vary 

 with the varying composition of the soil on which they grow, un- 



