14 



CULINAEY OR KITCHEN GARDEN. 



box, would be daily removed. The others 

 say the same droppings of the leaves, by 

 the general nourishment which they 

 supply, Tieutralise the particular excre- 

 tions. Liebig advocated the exhausting 

 principle, and showed, chemically, that 

 the roots of trees and plants in time ex- 

 haust those principles contained in the 

 soil which are most conducive to their 

 respective wants. This appears to be 

 both a conclusive and simple way of 

 settling the question. He afterwards 

 modified these views, and remarks, p. 33, 

 edit. 1843, "Transformations of existing 

 compounds are constantly taking place 

 during the whole life of a plant, in conse- 

 quence of which, and as the results of 

 these transformations, there are produced 

 gaseous matters which are excreted by the 

 leaves and blossoms, solid excrements de- 

 posited in the bark, and fluid soluble sub- 

 stances which are eliminated by the roots. 

 Such excretions are most abundant imme- 

 diately before the formation and during 

 the continuance of the blossoms; they 

 diminish after the development of the 

 fruit. Substances containing a large pro- 

 portion of carbon are excreted by the 

 roots and absorbed by the soil. Through 

 the expulsion of these matters, unfitted 

 for nutrition, the soil receives again, with 

 usury, the carbon which it had at first 

 yielded to the young plants as food, in 

 the form of carbonic acid. The soluble 

 matter thus acquired by the soil is still 

 capable of decay and putrefaction, and, 

 by undergoing these processes, furnishes 

 renewed sources of nutrition to another 

 generation of plants, and becomes humus." 

 We have many instances in practice, 

 where the same crop has been grown on 

 the same soil for many successive years, 

 vide article Onion; and many others 

 of a like kind could be adduced. Mr 

 Stephens, in his excellent "Book of the 

 Farm," vol. ii. p. 455, reasons on this 

 subject practically, and we think judi- 

 ciously. He says, " Experience has de- 

 monstrated that one crop after another of 

 the same kind greatly reduces the fertility 

 of all classes of soils. This conclusion 

 might be drawn from reason as well as 

 experience, since it is reasonable to sup- 

 pose that crops of the same kind take 

 the same sort of food out of the same 

 kind of soil. Experience has also demon- 

 strated that one crop after another, of a 



different kind, does not materially reduce 

 the condition of soils. This deduction, 

 then, seems fair, that the condition of the 

 soil is best maintained by taking different 

 crops after one another; and as every 

 crop, though of different kind, and deriv- 

 ing support from the soil, assists in ex- 

 hausting it, a limit must be put to the 

 number of crops that should follow one 

 another. Though all crops derive food 

 from the soil, one kind appropriates food 

 in a different degree from another; and 

 even the same crop takes food in different 

 quantities, according to the state its pro- 

 duct is allowed to proceed." Plants which 

 ripen their seed, as cabbages, turnips, &c., 

 when the ostensible object is to produce 

 seed, draw more strongly on the soil than 

 those which are grown for their leaves 

 and bulbs only, as spinach and beet, (fee. 

 Hence the practice, in gardens, of uselessly 

 allowing plants to shoot up into flower, 

 much less seed, in spring, cannot be too 

 severely reprobated. 



The excrementitious theory is ingenious, 

 if not even correct, and has occupied 

 the attention of the chemist for many 

 years. At the request of De Candolle, M. 

 Macaire of Geneva instituted a series of 

 experiments, which led him to conclude 

 that, in the formation of the seed, or other 

 nutritious parts of plants, the sap is di- 

 gested; that it takes up certain elements, 

 and deposits others, which are the residue 

 of the process ; and these, being no longer 

 necessary for the formation of the seed, 

 are rejected by the vital action of the 

 plant, and exude by the roots. " Our 

 ignorance of the functions of vegetable 

 life prevents us from seeing the effects 

 produced on the sap by the expansion of 

 the blossoms, or the ripening of the seed; 

 but experience leads us to perceive that 

 certain plants thrive best after certain 

 others, and that in this case they are 

 always of distinct and different natures, 

 and of different natural botanical families. 

 Macaire and other scientific men observed 

 the change that took place in the water 

 in which wheat had been made to grow. 

 They found a deposit in the water of the 

 nature of bitter extract, and this they 

 concluded to be excrementitious. Beans 

 grew well in this water; and, on the other 

 hand, wheat throve in the water in which 

 beans had grown." — Donaldson on Soils 

 and Manures, p. 30. The effects of fal- 



