PLANTATION, PLANTING. 



tificial means, so as to imitate more 

 natural circunislanccs. It is a well- 

 known fact that plants are subject to 

 a process of evaporation from all the 

 parts which arc exi)osed to the atmo- 

 sphere, provided tlie latter is not in 

 a state of saturation. The source 

 from wlience this evaporation is sup- 

 plied is the moisture of the soil, and 

 the roots are the media by which it 

 is collected and transmitted to the 

 stem branches and leaves. If the 

 expenditure be greater than the sup- 

 ply of moisture, the plant will begin 

 to suffer ; if the disparity be great 

 and continued, a degree of desicca- 

 tion will be occasioned sufficient to 

 deprive the vegetable tissue of that 

 moisture which constitutes the me- 

 dium of intercommunication between 

 the different cells ; organization is 

 destroyed ; the chain which connected 

 it with vitality is broken, and incapa- 

 ble of being reunited by any mechan- 

 ical means. 



"A much greater amount of evap- 

 oration takes place from a given sur- 

 face in some species than in others ; 

 but the amount as regards plants of 

 the same species, all other circum- 

 stances being the same, is in propor- 

 tion to the extent of surface which 

 the respective individuals possess. 

 The leaves of a lime-tree may have 

 a surface equal to thirty times that 

 of the stem, branches, and twigs 

 which produce them, and, conse- 

 quently, the demand on the roots for 

 the supply of evaporation will be 

 thirty times greater when in leaf 

 than when the branches are naked. 

 Instances might be adduced in which 

 this difference would even be exceed- 

 ed ; but if, on the contrary, it were 

 found considerably less, still there 

 would be sufficient evidence of the 

 impropriety of moving plants when 

 in leaf; and it may be here remark- 

 ed that young leaves admit of the 

 fluids being more rapidly evaporated 

 than old ones. 



" The month of December is that 

 in which the condition of the air with 

 regard to moisture approaches near- 

 est to that of complete saturation ; 

 and next in this respect is January, 

 582 



which is also the coldest. It might 

 therefore be concluded that these 

 months are the best for planting, 

 more especially as they arc the most 

 opposite in character to June and 

 July, which, from their being the hot- 

 test and driest, are found to be the 

 worst. But November is also moi.'it ; 

 and although the temperature of the 

 season has not then reached its min- 

 imum, yet the foliage, accustomed to 

 exercise its functions under a sum- 

 mer heat, can no longer perform them 

 under a reduction of temperature 

 which, though not the lowest, is 

 comparatively low as regards sum- 

 mer productions. The leaves, in 

 consequence, lose their connexion 

 with the roots ; the earth still re- 

 tains considerable warmth ; and al- 

 though the absence of leaves in de- 

 ciduous trees, and perhaps the in- 

 activity of those .of evergreens, may 

 prevent the formation of wood, ex- 

 cept in the most limited degree, yet 

 the buds, while they are themselves 

 increased in volume, maintain a cor- 

 responding action in the roots, suffi- 

 cient, in many instances, to form 

 fresh spongioles before winter : a 

 process which is favoured by the soil 

 being warmer than the atmosphere. 

 Should circumstances occur to pre- 

 vent the actual protrusion of cellular 

 substance in the form of spongioles, 

 still an accumulation of it will be ta- 

 king place, ready to burst forth in 

 spring. On this account, therefore, 

 although December, January, and 

 February are sufficiently moist, yet 

 November, or as soon as the leaves 

 have fallen, is the preferable season 

 for planting. There may be some 

 exceptions, as in the case of very 

 wet soils, where the plants, if not 

 firmly rooted, are liable to be thrown 

 out during winter, owing to which, 

 spring planting would be more prop- 

 er ; but, under ordinary circumstan- 

 ces, all deciduous trees will succeed 

 best at the period above indicated. 

 Such species as push forth their buds 

 early onght certainly to be planted 

 in autumn. Many of the coniferous 

 tril)e will succeed well if planted soon 

 after they have made their summer's 



