Book I. PRINCIPLES OF VEGETABLE CULTURE. 277 



or preservation of living specimens of these plants, therefore, in our green-houses and 

 stoves, is a rational entertainment, and also useful, as many species become in time ac- 

 climated, and some even naturalised ; and uses may in time also be discovered for such 

 as are now merely looked on as objects of curiosity. But it is quite enough to justify 

 much more than all the care that is taken to obtain and preserve them, that they contri- 

 bute to elegant enjoyment ; for what is life when it does not exceed mere obedience to 

 the animal instincts? 



1785. With respect to the native habitations of the exotic jyart of tfie British HortuSf 

 little can be advanced with certainty. In general it seems to appear that moist and mo- 

 derately warm climates, and irregular surfaces, are most prolific in species; and judging 

 of the whole world from Europe, we should venture to consider half the species of plants 

 in existence as growing in soft and rather moist grounds, whether low or elevated. The 

 soil of surfaces constantly moist, or inclining to be moist, whether watered from the at- 

 mosphere or from subterraneous sources, is almost always found to be minutely divided, 

 and generally of a black vegetable or peaty nature. Immense tracts in Russia and Ame- 

 rica are of this description, and even when dry, resist evaporation better than any other. 

 In such soils, the roots of plants are generally small and finely divided, as in the heaths, 

 most bog plants, and nearly all the American shrubs. The next sort of habitation most 

 prolific in species, appears to us to be arenarious soils in temperate climates, and in pro- 

 portion to their moisture. Here the roots of plants are also small, but less so than in 

 soils of the former description. On rocky and calcareous soils the roots of plants are ge- 

 nerally strong and woody, or at least long and penetratiug. In clayey habitations, ex- 

 clusive of the alluvial depositions of rivers, few plants are found, and these generally 

 grasses, or strong fibrous-rooted herbaceous plants, or tap-rooted trees. Such at least is 

 the amount of our generalisations ; but as our observation has been limited to Europe, 

 and does not even extend to the whole of it, those who have visited Africa and Asia are 

 much more capable of illustrating the subject. One conclusion we think the cultivator 

 is fully entitled to draw, that the greater number of plants, native or foreign, will thrive 

 best in light soil, such as a mixture of soft black vegetable mould or peat and fine sand 

 kept moderately moist ; and that on receiving unknown plants or seeds, of the native sites 

 of which he is ignorant, he will err on the safe side by placing them in such soils rather 

 than in any other ; avoiding, most of all, clayey and highly manured soils, as only fit 

 for certain kinds of plants constitutionally robust, or suited to become monstrous by 

 culture. 



Chap. VII. 

 Origin and Principles of Culture as derived from the Study of Vegetables. 



1786. The final object of all the sciences is their application to purposes subservient 

 to the wants and desires of men. The study of the vegetable kingdom is one of the 

 most important in this point of view, as directly subservient to the arts which supply 

 food, clothing, and medicine ; and indirectly to those which supply houses, machines 

 for conveying us by land, or by water, and in short almost every comfort and luxury. 

 Without the aid of the vegetable kingdom, few mineral bodies would be employed 

 in the arts, and the great majority of animals, whether used by man as laborers, or 

 as food, could not live. 



1787. Agriculture and gardening are the two arts which embrace the whole business 

 of cultivating vegetables, for whatever purpose they are applied by civilized man. 

 Their fundamental principles as arts of culture are the same ; they are for the most 

 part suggested, by nature, and explained by vegetable chemistry and physiology 

 (Chap. III. and IV.) ; and most of them have been put in practice by man for 

 an unknown length of time, without much reference to principles. All tliat is neces- 

 sary, therefore, for effecting this branch of culture, is to imitate the habitation, and to 

 propagate. This is, or ought to be the case, wherever plants are grown for medical or 

 botanical purposes, as in herb and botanic gardens. Nature is here imitated as exactly 

 as possible, and the result is, productions resembling, as near as possible, those of 

 nature. 



1788. To increase the number and improve the qualities of plants, it is necessary to faci- 

 litate their mode of nutrition by removing all obstacles to the progress of the plant. 

 These obstacles may either exist under or above the surface ; and hence the origin of 

 draining, clearing from surface-incumbrances, and the various operations, as digging, 

 ploughing, &c. for pulverising the soil. Nature suggests this in accidental ruptures 

 of the surface, broken banks, the alluvial depositions from overflowing rivers, and 

 die earth thrown up by underground animals. Many of the vegetables within the 



