Excerpta Botanica. 475 



were considered to constitute a fertile soil ; the compound was 

 well watered and planted with several vegetables ; they how- 

 ever would not thrive till the water was changed for the 

 drainings of a dunghill. Plants have been placed in a variety 

 of substances, as sulphur, pounded glass, &c., and carefully 

 moistened with distilled water ; in this state they have existed 

 for some time, but it is beyond all experience to suppose, that, 

 in such a condition, they should perfect the several functions 

 required of them by nature. It is only by a proper supply of 

 organized matter in the soil that vegetation can proceed with 

 vigour ; some portion of this is supplied by animals, but by 

 far the greater and more important is yielded by plants, which 

 is thus returning to the form and uses from which it had pre- 

 viously issued. 



Every year brings in the alternation of its seasons changes 

 in the vegetable kingdom ; as soon as spring has set in new 

 life is given to every herb and shrub, the buds unfold, deve- 

 loping flowers and leaves ; the former soon fade and fall, in 

 time the fruit follows, and towards the end of summer the 

 rising winds drive the leaves in clouds from the trees. Heavy 

 rains now succeed, and the broken branches, portions of shed 

 bark and other vegetable remains, the refuse of the autumn, 

 are soon saturated with moisture and hasten to decomposi- 

 tion. In countries with excessively moist climates the quan- 

 tity of fallen vegetation is immense ; large trees, the noblest 

 members of the forest, sinking under the effects of a con- 

 tinually moist atmosphere, literally lie in tiers, and give a foot- 

 ing, though often a treacherous one, for hundreds of yards 

 without it being necessary to touch the soil. A portion of 

 this decaying matter is dissolved by the rain-water, and pene- 

 trating the earth carries nutriment to the roots against the de- 

 mands of the ensuing spring. What remains gradually mixes 

 with the mineral constituents of the soil, and more slowly be- 

 comes subservient to the same end. 



[To be continued.] 



LII. — Excerpta Botanica, or abridged Extracts translated 

 from the Foreign Journals, illustrative of, or connected with, 

 the Botany of Great Britain. By W. A. Leighton, Esq., 

 B.A., F.B.S.E., &c. 



No. 10. Revisio Tiliarum, Auctore Eduardo Spach. (Ann. 

 des Sc. Nat. vol. ii. n. s. p. 381.) [So far as respects our 

 British species.] 



TILIA, Linn. 

 Arbores, coma subrotunda vel ovah, densissima. Cortex interior 



flexilis, tenax. Lignum laeve. Ramuli saep^ ab autumno ad ver 



2 12 



