556 



Agricultural Chemistry — Turnips. 



and with the most ash and most nitrogen, the least dry matter. 

 Tlie relative tendency to bulbous deposition, or active vascular 

 circulation, under carbonaceous and nitrogenous manures respect- 

 ively, is here again exhibited. 



It will be remembered that the specimens of turnip-leaf which 

 were examined, were gathered very late in the season — the few 

 that could be selected green being taken. All were, however, 

 far advanced in stage of growth, and it was found that, whether 

 ov.ing to an uniformity in the stage of growth, or to the essential 

 tendency of the leaves, as different from that of the bulb, there 

 was very little variation in the proportion of dry matter, compared 

 with that observed in the bulbs. The following m.ean results will 

 illustrate this : — 



Reference to History of the SpecimeDs. 



Percentage 

 of Dry 

 Matter in 

 Leaf. 



Percenta>;e 

 of Ash in 

 Fresh 

 Leaf. 



Percentage 

 of Ash iu 

 Dry 

 Matter. 



Mean of 9, 1-1, 18, 21, and 22, with mineral manures! 



Mean of 9, 14, 18, 21, and 22, with mineral manuresl 



Mean of 9, 14, 18, 21, and 22, with mineral manures,! 

 rape-cake, and ammoniacal salt J 



13-73 

 13-31 

 12-87 



1-31 

 1-26 

 1-25 



9-52 

 9-49 

 9-72 



The differences here seen are, as we have already implied, 

 small ; nor are the results so undoubted in their bearing as most 

 that have been quoted ; yet still we have with the smallest amount 

 of dry matter, the largest per centage of ash in the dry matter. 

 The centre column shows the lowest percentage of ash in the 

 fresh leaf in this case ; but it is of course the percentage to icater, 

 rather than to dry vegetable substance, that is there indicated. 



The comparative ash results that have been given, whether of 

 the turnip-bulb or leaf, lead us then yet again to draw some distinc- 

 tions between the fixed and the circulating constituents of a suc- 

 culent plant, and to trace the proportion of these respectively to 

 the stage of maturity of the organ, whilst this has been found to 

 depend greatly upon the supply by manure. 



Were we to compare the composition of the leaf, as thus far 

 shown, with that of the bulb, and to attempt to apply on all points 

 the same kind of reasoning as between bulb and bulb, or leaf and 

 leaf, we should at once meet with inconsistencies, for we find in 

 the earlier product of the plant — the leaf — a much larger amount 

 of dry matter than in the later one — the bulb. And again, with 

 the higher percentage of dry matter in the leaf, we have at the 

 same time a much larger amount of ash in that dry matter. Such 

 comparisons are, however, physiologically, quite inadmissible. 

 Looking- at the question in another view, however^ we have attri- 



