124 The Limestones, and Lime. [March, 



or animals. It may be absorbed, however, in the form and state 

 of a super-carbonate, because in this state it is soluble; still, even 

 then we believe it requires a different combination, in order to 

 fulfd the functions required of it in the vegetable kingdom. 



One of the great obstacles which seem to have prevented most 

 writers from seeing the uses of lime to plants, is the insolubility 

 of some of its compounds, especially when they are prepared in 

 the laboratory of the chemists. Coupling this fact with another, 

 viz., that the food of vegetables must be dissolved, and that they 

 cannot receive solid matter into their structures, it is by no means 

 strange that the compai-atively insoluble nature of some of the 

 calcareous compounds should lead many to infer that so far as 

 their use in the vegetable economy is concerned, they are of little 

 value; and that their use can be dispensed with. Even admit- 

 ting that they are important and necessary, it will be seen that, 

 in the view of many, their importance is confined to the guarding 

 of outposts, and that they are not designed to act within and help 

 build up the citadel. 



If insolubility of the calcareous compounds must be received 

 as a bar to the performance of other functions than those which 

 have been ennumerated by Towers and Fownes, then certainly, 

 the same objection must be made to silex; for, of all substances, 

 this is the most insoluble of the materials; and yet it is largely 

 absorbed by plants, especially by the cereals, and the monocoty- 

 ledonous plants generally. 



But it is a fortunate thing that the laboratory of nature is quite 

 different in its arrangements, and that its powers are quite supe- 

 rior to the laboratories even of a Berzelius or a Liebig. Now, in the 

 earth, or the laboratory first referred to, the chemical changes go 

 on in continuous circles. As an illustration of our meaning, the 

 waters beneath flow upward in invisible vapors, until the air 

 above approaches to a saturation, when the currents are reversed 

 by the descent of showers of visible rain, which saturate in their 

 turn the earth; or the springs and rills flow outward to the sea in 

 ceaseless streams, while the supply of the internal fountain is 

 kept full by vapors from the broad ocean flowing upward first, 

 and then downward to the earth, and sinking into its depths 

 profound. 



These movements of mist and rain serve an important pur- 

 pose: they continually bring the active elements required in the 

 vegetable economy into a nascent state; a state in which nutrient 

 matter is made ready and prepared for the vegetable's use. This 

 state is a transient one, and is in one sense incomplete; or it is 

 that state in which the elements are in the act of combining; or 

 we may better say, in a state in which they are disposed to com- 

 bine. Oxygen and hydrogen confined in a tube, will never unite 



