276 VEGETABLE FOOD. 



of vegetable and animal matter that can be collected 

 and incorporated together, in order that the crop, 

 whatever it may be, may have the power of 

 selection. 



The luxuriance or weight of a crop is always in 

 proportion to the richness of the soil, or to the quan- 

 tity of manure bestowed, other circumstances being 

 favourable ; but it is usually apportioned to the nature 

 of the crop intended to be raised. If bulk of stem, 

 leaves, or roots, is the object, it is scarcely possible 

 to give too much ; but if for superior grain or fruit, 

 moderate quantities answer best. 



In whatever way manure be applied, whether by 

 incorporating it with the soil, or diluted in water, the 

 effect on the plant is the same ; every part, viz. 

 root, stem, leaves, flower, and fruit, are enlarged, 

 showing that either the vegetative vigour receives 

 extraordinary excitement, or that the juices become 

 more copious, so that their power of distension is in- 

 creased. Stronger and accelerated growth is the eifect, 

 and no doubt caused by the additional supplies of 

 aqueous and gaseous elemental bodies essential to the 

 plant which are afforded by the manure ; but whether 

 these supplies be carbon only, or a combination of 

 various chemical principles collected by the spongioles, 

 and so imbibed together, we have yet to learn. One 

 thing is very certain, that all substances used as ma- 

 nure, are more or less effectual according as they are 

 more or less attractive, and retentive of humidity. 



Respecting the effects of fallowing, it is quite evi- 



