38 



CASSELL'S POPULAR GARDENING. 



of the Artichoke give 28 Iha. of ash, while an equal 

 weight of the dried tubers will give less than 5^ lbs. 

 of ash when burnt. Mineral ingredients are abundant 

 in succulent foliage, but are found in small propor- 

 tions in seeds, wood, and bark ; and the nearer we 

 approach to the elaboration of the final products of 

 the plant — the seed — the more constant is the quantity 

 and composition of ash in one and the same species. 



(c) The timber of freely-growing trees yields but 

 a small proportion of ash, while the leaves, and 

 especially the autumnal leaves, contain a consider- 

 able amount — sometimes as much as 20 per cent, of 

 the dry matter or water-free substance. 



The leaves which fall in autumn have been found, 

 on analysis, to have lost nearly all their starch, 

 albuminoids, phosphoric acid, and potash, these 

 having been transferred to the stem. By the action 



of the sun in spring-time, the new buds swell, the 

 sap rises, the starch and other matters deposited in 

 the wood during the previous autumn are re-dissolved, 

 and are utilised by the plant for the production of 

 new growth during the summer. 



Ash ingredients necessary to plant-life. — A know- 

 ledge of the composition of the ashes of plants is 

 most essential in a practical point of view, as indi- 

 cating the mineral constituents which particular 

 plants abstract from the soil in order to build up 

 their structure, and as a guide in judiciously select- 

 ing the manure most suited to their wants, for it is 

 utterly impossible to attempt producing a plant at all 

 without some ash-ingredients are present in the soil. 



The following table shows the percentage chemical 

 composition of the ashes derived from various plants, 

 or separated portions of plants, when burnt : — 



Composition of 100 Parts op the Ashes op Plants. 



A simple inspection of the above results leads to 

 various interesting conclusions. "Were the ashes of 

 every plant or portion of a plant the same in quantity 

 and composition, a knowledge of the gross produce in 

 any given case would suffice to indicate the amount 

 of mineral exhaustion that had taken place in the 

 soil. This, however, is anything but the actual state 

 of things. The separate portions of plants differ in 

 their mineral composition fully as much as one entire 

 plant does from another. 



Thus we find that, while potash salts predominate 

 most in the under-ground portion of the plants 

 enumerated, lime exists in the largest quantity in 

 the Stem and leaf, the above - gi-ouud growth. 

 Therefore we find it is to a considerable degree the 

 character or fertility of the soil which determines 

 the -vigour of the plant grown, and the relative 



development of its parts. The proportion of lime 

 varies within very wide limits, being in some plants 

 as low as 1 and in others reaching over 40 per cent, 

 of the ash. From some experiments recently made 

 in Germany on the beneficial effect of lime tft 

 plant-growth, it appears that most seeds -will germi- 

 nate without this ingredient being present in the 

 soU; but, although the young plants spring up and 

 form their first leaves, they soon become yellow, 

 wither, and die. 



Ho-w- Plants Peed Plants obtain the ele- 

 ments of which they are composed partly from the 

 soil and partly from the atmosphere. From the soil 

 they obtain, by means of their roots, all the incom- 

 bustible constituents which are found, in its ash, and 

 nearly the whole of their nitrogen and water. From 



