Part 6

The Tin Cover was to prevent any other Earth from getting in. This must also prevent any Earth from getting out, except what enter’d the Roots, and by them pass’d into the Tree.

A Willow is a very thirsty Tree, and must have drank in Five Years time several Tuns of Water, which must necessarily carry in its Interstices a great Quantity of Earth (probably many times more than the Tree’s Weight, which could not get out, but by the Roots of the Willow.

The Body of an Animal receives a much less Increase in Weight than its Perspirations amount to, as Sanctorius’s Static-Chair demonstrates.

Therefore the Two hundred Pounds of Earth not being increased, proves that so much Earth as was poured in with the Water, did enter the Tree.

Whether the Earth did enter to nourish the Tree, or whether only in order to pass through it (by way of Vehicle to the Air), and leave the Air behind for the Augment of the Willow, may appear by examining the Matter of which the Tree did consist.

If the Matter remaining after the Corruption or Putrefaction of the Tree be Earth, will it not be a Proof, that the Earth remained in it, to nourish and augment it? for it could not leave what it did not first take, nor be augmented by what pass’d through it. According to Aristotle’s Doctrine, and Mr. Bradley’s too, in Vol. I. pag. 72. “Putrefaction resolves it again into Earth, its first Principle.”

The Weight of the Tree, even when green, must consist of Earth and Water. Air could be no Part of it, because Air being of no greater specific Gravity than the incumbent Atmosphere, could not be of any Weight in it; therefore was no Part of the One hundred Sixty-nine Pounds Three Ounces.

Nature has directed Animals and Vegetables to seek what is most necessary to them. At the Time when the Fœtus has a Necessity of Respiration, ’tis brought forth into the open Air, and then the Lungs are filled with Air. As soon as a Calf, Lamb, &c. is able to stand, it applies to the Teat for Food, without any Teaching. In like manner Mr. Bradley remarks, in his Vol. I. pag. 10. ‘That almost every Stem and every Root are formed in a bending manner under Ground; and yet all these Stems become strait and upright when they come above-ground, and meet the Air; and most Roots run as directly downwards, and shun the Air as much as possible.’

Can any thing more plainly shew the Intent of Nature, than this his Remark does? viz. That the Air is most necessary to the Tree above ground, to purify the Sap by the Leaves, as the Blood of Animals is depurated by their Lungs: And that Roots seek the Earth for their Food, and shun the Air, which would dry up and destroy them.

No one Truth can possibly contradict or interfere with any other Truth; but one Error may contradict and interfere with another Error, viz.

Mr. Bradley, and all Authors, I think, are of Opinion, that Plants of different Natures are fed by a different Sort of Nourishment; from whence they aver, that a Crop of Wheat takes up all that is peculiar to that Grain; then a Crop of Barley all that is proper to it; next a Crop of Pease, and so on, ’till each has drawn off all those Particles which are proper to it; and then no more of these Grains will grow in that Land, till by Fallow, Dung, and Influences of the Heavens, the Earth will be again replenish’d with new Nourishment, to supply the same Sorts of Corn over again. This, if true (as they all affirm it to be), would prove, that the Air is not the Food of Vegetables. For the Air being in itself so homogeneous as it is, could never afford such different Matter as they imagine; neither is it probable, that the Air should afford the Wheat Nourishment more one Year, than the ensuing Year; or that the same Year it should nourish Barley in one Field, Wheat in another, Pease in a Third; but that if Barley were sown in the Third, Wheat in the First, Pease in the Second, all would fail: Therefore this Hypothesis of Air for Food interferes with, and contradicts this Doctrine of Necessity of changing Sorts.

I suppose, by Air, they do not mean dry Particles of Earth, and the Effluvia which float in the Air: The Quantity of these is too small to augment Vegetables to that Bulk they arrive at. By that way of speaking they might more truly affirm this of Water, because it must be like to carry a greater Quantity of Earth than Air doth, in proportion to the Difference of their different specific Weight; Water, being about 800 times heavier than Air, is likely to have 800 times more of that terrestrial Matter in it; and we see this is sufficient to maintain some Sort of Vegetables, as Aquatics; but the Air, by its Charge of Effluvia, &c. is never able to maintain or nourish any Plant; for as to the Sedums, Aloes, and all others, that are supposed to grow suspended in the Air, ’tis a mere Fallacy; they seem to grow, but do not; since they constantly grow lighter; and tho’ their Vessels may be somewhat distended by the Ferment of their own Juices which they received in the Earth, yet suspended in Air, they continually diminish in Weight (which is the true Argument of a Plant) until they grow to nothing. So that this Instance of Sedums, &c. which they pretend to bring for Proof of this their Hypothesis, is alone a full Confutation of it.

Yet if granted, that Air could nourish some Vegetables by the earthy Effluvia, &c. which it carry’d with it ; even that would be against them, not for them.

This is meant of dry Earth, by its Lightness (when pulveriz’d extremely fine) carried in the Air without Vapour: For the Atmosphere, consisting of all the Elements, has Earth in it in considerable Quantity, mix’d with Water; but a very little Earth is so minutely divided, as to fly therein pure from Water, which is its Vehicle there for the most Part.

They might as well believe, that Martins and Swallows are nourish’d by the Air, because they live on Flies and Gnats, which they catch therein; this being the same Food, which is found in the Stomach of the Chameleon.

If, as they say, the Earth is of little other Use to Plants, but to keep them fix’d and steady, there would be little or no Difference in the Value of rich and poor Land, dung’d or undung’d; for one would serve to keep Plants fix’d and steady, very near, if not quite as well as the other.

If Water or Air was the Food of Plants, I cannot see what Necessity there should be of Dung or Tillage.

4. Fire. No Plant can live without Heat, tho’ different Degrees of it be necessary to different Sorts of Plants. Some are almost able to keep Company with the Salamander, and do live in the hottest Exposures of the hot Countries. Others have their Abode with Fishes under Water, in cold Climates: for the Sun has his Influence, tho’ weaker, upon the Earth cover’d with Water, at a considerable Depth; which appears by the Effect the Vicissitudes of Winter and Summer have upon subterraqueous Vegetables.

Tho’ every Heat is said to be a different Degree of Fire; yet we may distinguish the Degrees by their different Effects. Heat warms; but Fire burns: The first helps to cherish, the latter destroys Plants.

5. Earth. That which nourishes and augments a Plant is the true Food of it.

Every Plant is Earth, and the Growth and true Increase of a Plant is the Addition of more Earth.

Nitre (or other Salts) prepares the Earth, Water and Air move it, by conveying and fermenting it in the Juices; and this Motion is called Heat.

When this additional Earth is assimilated to the Plant, it becomes an absolute Part of it.

Suppose Water, Air, and Heat, could be taken away, would it not remain to be a Plant, tho’ a dead one?

But suppose the Earth of it taken away, what would then become of the Plant? Mr. Bradley might look long enough after it, before he found it in the Air among his specific or certain Qualities.

Besides, too much Nitre (or other Salts) corrodes a Plant; too much Water drowns it; too much Air dries the Roots of it; too much Heat (or Fire) burns it; but too much Earth a Plant never can have, unless it be therein wholly buried; and in that Case it would be equally misapply’d to the Body, as Air or Nitre would be to the Roots.

Too much Earth, or too fine, can never possibly be given to Roots; for they never receive so much of it as to surfeit the Plants, unless it be depriv’d of Leaves, which, as Lungs, should purify it.

And Earth is so surely the Food of all Plants, that with the proper Share of the other Elements, which each Species of Plants requires, I do not find but that any common Earth will nourish any Plant.