THE ASII OF PLANTS. 105 



gradients, viz. chlorine and sulphuric acid, should be re- 

 duced to uniformity, and the analyses then be recalculated 

 to per cent. 



In the first place, however, we are not warranted in 

 assuming that the " excess " of chloride of potassium, car- 

 bonate of potash, etc., deducted in the above analyses 

 respectively, was all accidental and unnecessary to the 

 plant, for, under the influence of an increased amount of a 

 nutritive ingredient, the plant may not only mechanically 

 contain more, but may chemically employ more in the 

 vegetative processes. It is Avell proved that vegetation 

 grown under the influence of large supplies of nitrogenous 

 manures, contains an increased proportion of nitrogen in 

 the truly assimilated state of albumin, gluten, etc. The 

 same may be equally true of the various ash-ingredients. 



Again, in the second place, we cannot say that in any 

 instance the mmimttm quantity of any ingredient neces- 

 sary to the vegetative act is present, and no more. 



It must be remarked that these great variations are only 

 seen when we compare together plants produced oupoor 

 soils, i. e. on those which are relatively deficient in some 

 one or several ingredients. If a fertile soil had been em- 

 ployed to support the buckwheat plants in these trials, we 

 should doubtless have had a very different result. 



In 1859, Metzdorf, ( Wildcts CentralUatt, 1862, 2, p. 

 367,) analysed the ashes of eight samples of the red-onion 

 potato, grown on the same field in Silesia, but differently 

 manured. 



Without copying the analyses, we may state some of 

 the most striking results. The extreme range of variation 

 in potash was 5| per cent. The ash containing the high- 

 est percentage of potash was not, however, obtained from 

 potatoes that had been manured with 50 pounds of this 

 substance, but from a parcel to which had been applied a 

 poudrette containing less than 3 pounds of potash for the 

 quantity used. 



