If any one of these Three Propositions be true, as I hope to prove all of them are, then it will follow, that there is no need to change the Species of Vegetables from one Year to another, in respect to the different Food the same Soil is, tho’ falsely, supposed to yield[201].

The common Opinion is contrary to all these (as it must be, if contrary to any one of them): And since an Error in this fundamental Principle of Vegetation is of very ill Consequence; and since Dr. Woodward, who has been serviceable in other respects[202] to this Art, has unhappily fallen in with the Vulgar in this Point; his Arguments for this Error require to be answer’d in the first Place.

The Doctor says[203] ‘It is not possible to imagine how one uniform, homogeneous Matter, having its Principles, or original Parts, all of the same Substance, Constitution, Magnitude, Figure, and Gravity, should ever constitute Bodies so egregiously unlike, in all those Respects, as Vegetables of different Kinds are; nay, even as the different Parts of the same Vegetable.’

‘That there should be that vast Difference in them, in their several Constitutions, Makes, Properties, and Effects, and yet all arise from the very same Sort of Matter, would be very strange.’

Answer. ’Tis very probable, that the terrestrial Particles which constitute Vegetables, tho’ inconceivably minute, may be of great Variety of Figure, and other Differences; else they could not be capable of the several Ferments, &c. they must undergo in the Vessels of Plants. Their Smalness can be no Objection to their Variety, since even the Particles of Light are of various Kinds.

But as the Doctor asserts, ‘That each Part of the same Vegetable requires a peculiar specific Matter for its Formation and Nourishment; and that there are very many and different Ingredients to go to the Composition of the same individual Plants;’

From hence must be inferred, that the same Plant takes in very many and different Ingredients (and it is proved, that no Plant refuses any Ingredient[204] that is capable of entering its Roots. Tho’ the terrestrial Particles which nourish Vegetables, be not perfectly homogeneous; yet most of the various Tastes and Flavours of Plants are made in and by the Vessels[205].

Doctor Woodward says, ‘That Water will pass Pores and Interstices, that neither Air, nor any other Fluid, will: This enables it to enter the finest Tubes and Vessels of Plants, and to introduce the terrestrial Matter, conveying it to all Parts of them; whilst each, by means of Organs ’tis endow’d with for the Purpose, intercepts, and assumes into itself, such Particles as are suitable to its own Nature[206]; letting the rest pass on through the common Ducts.’

Here then he says plainly, That each Plant receives the terrestrial Matter in gross, both suitable and unsuitable to its Nature, retains the suitable Particles for its Augment, and the unsuitable lets pass through it. And in another Place he says they are exhal’d into the Atmosphere.

And this will appear to be the true Case of Plants; and directly contradicts what he advances, in saying, ‘That each Sort of Grain takes forth that peculiar Matter that is proper for its own Nourishment. First, the Wheat draws off those Particles that suit the Body of that Plant, the rest lying all quiet and undisturb’d the while. And when the Earth has yielded up all them, those that are proper for Barley, a different Grain, remain still behind, till the successive Crops of that Corn fetch them forth too; and so the Oats and Pease in their turn, till, in fine, all is carried off.’

In the former Paragraph he says, each Plant lets pass through it the rest of the Particles that are not suitable to its own Nature. In the latter Paragraph he says, That each leaves the unsuitable all behind for another Sort; and so on.

Both cannot be true.

If the latter were true, Change of Sorts would be as necessary as it is commonly thought. But if the former be true, as I hope to prove it is, then there can be no Use of changing of Sorts in Respect of different Nourishment.

If in this Series of Crops each Sort were so just as to take only such Particles, as are peculiarly proper to it, letting all the rest alone to the other Sorts to which they belonged, as the Doctor imagines; then it would be equal to them all, which of the Sorts were sown first or last: But let the Wheat be sown after the Barley, Pease, and Oats, instead of being sown before them, and then it would evidently appear, by that starv’d Crop of Wheat, either that some or all of those other Grains had violated this natural Probity, or else that Nature has given to Vegetables no such Law of Meum and Tuum[207].

If these Things were, as the Doctor affirms, why do Farmers lose a Year’s Rent, and be at the Charge of fallowing and manuring their Land, after so few Crops; since there are many more Sorts of Grain as different from these and one another, as those are which they usually sow?

They still find, that the first Crops are best; and the longer they continue sowing, the worst the last Crops will prove, be they of never so different a Species; unless the Land were not in so good Tilth for the first Crop as for the subsequent; or unless the last sown be of a more robust Species.

This Matter might be easily clear’d, could we perfectly know the Nature of those supposed unsuitable[208] Particles; but, in Truth, there is no more to be known of such of them, than that they are carried away by the Atmosphere to a Distance, according to the Velocity of the Air; perhaps several Miles off, at least, never like to return to the Spot of Ground from whence the Plants have raised them.

But suppose these cast-off Particles were, when taken in, unfit for the Nourishment of any manner of Vegetables: Then the Doctor must fansy the Wheat to be of a very scrupulous Conscience, to feed on these Particles, which were neither fit for its own Nourishment, nor of any other Plant; and at the same time to forbear to take the Food of Barley, Pease, and Oats, letting that lie still and undisturb’d the while, as he says it does, tho’ he gives no manner of Reason for it.

’Tis needless to bring stronger Arguments, than the Doctor’s Experiments afford, against his own vulgar Opinion, of Plants distinguishing the particular Sort of terrestrial Matter, that, he says, is proper to each Sort of Vegetable, in these Words; viz. ‘Each Sort takes forth that peculiar Matter that is proper for its own Nourishment, the rest lying all quiet and undisturb’d the while.’

He says, that great Part of the terrestrial Matter, mixed with the Water, passes up into the Plant along with it; which it could not do, if only the peculiar Matter, proper to each Plant, did pass up into it: And after he has shewed how apt the vegetable Matter is to attend Water in all its Motions, and to follow it into each of its Recesses; being by no Filtrations or Percolations wholly separable from it; ’tis strange he should think that each Plant leaves the greatest Part of it behind, separated from the Water which the Plant imbibes.

There are, doubtless, more than a Million of Sorts of Plants, all of which would have taken up the Water, and had each as much Right to its Share, or proper Matter in it, as the Doctor’s Plants had; and then there would be but a very small (or a Millionth) Part of it proper to each of his Plants: And these leaving all the rest behind, both of the Water wherewith the Glasses at first were filled, when the Plants were put into them; and also of all the additional Water daily supply’d into them afterwards; I say, so much more terrestrial Matter brought into these Glasses, in Proportion to the added Water, and so very small a Part as could be proper to each of his plants being carried off; there must have remain’d in these Glasses a much greater Quantity of terrestrial Matter at the End of the Experiment, than remained in the Glasses F or G, which had no Plants in them, nor any Water added to, or diminished from them; but the quite contrary appear’d. ‘And the Water in the Glasses F and G, at the End of the Experiment, exhibited a larger Quantity of terrestrial Matter, than any of those that had Plants in them did. The Sediment at the Bottom of the Glasses was greater, and the Nubeculæ diffused thro’ the Body of the Water thicker.’ Had the Cataputia insum’d, with the Two thousand Five hundred and One Grains of Water, no more than its proper Share of the vegetable Matter, it could not have attained thence an Increase of Three Grains and a Quarter, nor even the Thousandth Part of One Grain. But he found ‘this terrestrial Matter, contained in all Water, to be of Two Kinds: The one properly, a vegetable Matter, but consisting of very different Particles; some of which are proper for the Nourishment of some kind of Plants, others for different Sorts,’ &c.

This, indeed, would have been a most wonderful Discovery, and might have given us a great Light, if he had told us in what Language and Character these proper Differences were stamp’d or written upon the vegetable Particles; which Particles themselves, he says, were scarce visible. Certainly it must be a great Art (much beyond that of Dr. Wallis) to decypher the Language of Plants, from invisible Characters.

But that this Dream may deceive none, except such who are very fond of old Errors, there is an Experimentum Crucis which may convince them; viz. At the proper Season, tap a Birch-tree in the Body or Boughs, and you may have thence a large Quantity of clear Liquor, very little altered from Water; and you may see, that every other Species of Plants, that will grow in Water, will receive this; live and grow in it, as well as in common Water. You may make a like Experiment by tapping other Trees, or by Water distilled from Vegetables; and you will find no Species of Plants, into which this Water will not enter, and pass through it, and nourish it too; unless it be such a Species as requires more Heat than Water admits; or unless the peculiar Vessels of that it has first passed through, have so altered the vegetable Particles contained in that Water, as that it acts as Poison upon some other particular Species.

The Doctor concludes, ‘That Water is only the Agent that conveys the Vegetable Matter to the Bodies of Plants, that introduces and distributes it to their several Parts for their Nourishment: That Matter is sluggish and inactive, and would lie eternally confin’d to its Beds of Earth, without ever advancing up into Plants, did not Water, or some like Instrument, fetch it forth, and carry it unto them.’

That Water is very capable of the Office of a Carrier to Plants, I think the Doctor has made most evident; but as to the Office of such an Agent as his Hypothesis bestows upon it, it seems impossible to be executed by Water. For it cannot be imagined, that Water, being itself but mere homogenial Matter, void of all Degrees of Life, should distinguish each Particle of vegetable Matter, proper and peculiar to every different Species of Plants, which are innumerable; and when ’tis to act for the Wheat, to find out all the Particles proper to that sort of Grain, to rouse only those particular Sluggards from their Beds of Earth, letting all the rest lie quiet and undisturbed the while. This Agent frees the Wheat-Particles from their Confinement, and conveys, introduces, and distributes them, and only them, into the several Parts of the Wheat.

Since ’tis unreasonable to believe, that Water can have such extraordinary Skill in Botany, or in Micrography, as to be qualified for a sufficient Agent in such an abstruse Matter, I conceive Water to be only an Instrument or Vehicle, which takes up indifferently any Particles it meets with (and is able to carry), and advances them (or the Pabulum they yield) up into the First Plant, whose Root it comes in Contact with; and that every Plant it meets with does accept thereof, without distinguishing any different Sorts or Properties in them, until they be so far introduc’d and advanc’d up into the vegetable Vessels, that it would be in vain to distinguish them; for whether the terrestrial Matter, Plants imbibe with the Water, will kill or nourish them, appears by its Effects; but which cannot be foreknown or prevented without the Help of Faculties, which Plants are not endow’d with.

Mr. Bradley seems to have carried this Error farther than any Author ever did before; but he supports it by Affirmations only, or by such Arguments (I cannot say Reasons; for no Reason can be against any Truth) as go near to confute the very Opinion he pretends to advance by them.

He ascribes to Vegetables the Sense of Taste, by which he thinks they take such Nourishment as is most agreeable to their respective Natures, refuting the rest; and will rather starve, than eat what is disagreeable to their Palate.

In the Preface to his Vol. I. Page 10. of his Husbandry and Gardening, he says, ‘They feed as differently as Horses do from Dogs, or Dogs from Fish.’

But what does he mean by this Instance, Vol. I. p. 39. viz. ‘That Thyme, and other Aromatics, being planted near an Apricot-tree, would destroy that Tree?’ Does it not help to confirm, that every Plant does not draw exactly the same Share of Nourishment?

I believe there is no need for him to give more Instances to disprove his Assertion than this one. His Conclusion, taken by itself, is so far right; viz. ‘That if the Nourishment the Earth afforded to the Thyme and Apricot-tree, had been divided into Two Shares, both could not have had them.’

But this his Instance proves, That those Aromatics robb’d the Apricot-tree of so much of its Share as to starve it; and that they, tho’ of so very different a Nature, did draw from the Earth the same Nourishment which the Apricot-tree should have taken for its Support, had not the Aromatics been too hard for it, in drawing it off for their own Maintenance:

Unless he believes, that all the Juices of the Aromatics were as Poison to the Apricot; and that, according to my Experiment of the Mint, some of their Roots might discharge some kind of Moisture in dry Weather, given them by others, that had it for their Use; and that the Apricot-roots, mingling with them, might imbibe enough of that Liquor, altered sufficiently by their Vessels, to poison and kill the Tree.

But then, where was the Tree’s distinguishing Palate? Why did it not refuse this Juice, which was so disagreeable as to kill it? And as to his Notion of Vegetables having Palates, let us see how it agrees with what he affirms.

‘That ’tis the Vessels of Plants that make, by their Filtrations, Percolations, &c. all the different Tastes and Flavours of the Matter, which is the Aliment of Plants; and that, before it be by them so filtred, &c. it is only a Fund of insipid Substance, capable of being altered by such Vessels, into any Form, Colour, or Flavour.’

And Vol. I. p. 38. ‘The different Strainers, or Vessels of the several Plants, growing upon that Spot of Earth, thus impregnated with Salts, alter those Salts or Juices, according to the several Figures or Dimensions of their Strainers; so that one Plant varies, in Taste and Smell, from others, tho’ all draw their Nourishment from the same Stock lodged in the Earth.’ See Mr. Bradley’s Palates of Plants, and the insipid Substance he allots them to distinguish the Taste of, how they agree.

They must, it seems, within their own Bodies, give the Flavour to this insipid Substance, before their Palates can be of any Use; and, even then, ’tis impossible to be of any Use, but in the manner of the Dog returning to his Vomit.

They would have as much Occasion for the Sense of Smelling, as of Taste; but, after all, of what Use could either of the Two be to Plants, without local Motion of their Roots? which they are so destitute of, that no Mouth of a Root can ever remove itself from the very Point where it was first formed, because a Root has all its longitudinal Increase at the very End; for, should the Spaces betwixt the Branchings increase in Length, those Branches would be broken off, and left behind, or else drawn out of their Cavities; which must destroy the Plant. All the Branches, except the foremost, would be found with their Extremities pointing towards the Stem; the contrary of which Posture they are seen to have: And if they moved backwards, that would have much the same Effect on all the collateral Branchings to destroy them. Smell and Taste then could be of no manner of Use to Vegetables, if they had them; they would have no Remedy or Possibility to mend themselves from the same Mouths, removing to search out other Food, in case they had Power to dislike or refuse what was offered them.

Therefore the crude Earth, being their Food, simple and free from any Alterations by Vessels, remaining insipid, cannot give, neither can Plants receive, require, or make use of, any Variety from it, as Animals do from their Diet. It would be lost upon them, and Nature would have acted in vain, to give Smell and Taste to Vegetables, and nothing but insipid Earth for an Object of them; or to give them a charming Variety of Relish and Savour in their Food, without giving them Senses necessary to perceive or enjoy them; which would be like Light and Colours to the Blind, Sound and Music to the Deaf, or like giving Eyes and Ears to Animals, without Light or Sound to affect them.

The Mouths of Plants, situate in the convex Superficies of Roots, are analogous to the Lacteals, or Mouths, in the concave Superficies of the Intestines of Animals.

These spongy Superficies of animal Guts, and vegetable Roots, have no more Taste or Power of refusing whatever comes in Contact with them, the one than the other.

The free open Air would be equally injurious to both; and if exposed to it, it would dry and close up the fine Orifices in Guts and Roots: Therefore Nature has guarded both from it.

Nature has also provided for the Preservation of both Vegetables and Animals (I do not say equally) in respect of their Food; which might poison them, or might not be fit to nourish them.

The Security of Plants (the best that can be) is their Food itself, Earth; which, having been altered by no Vessels, is always safe and nourishing to them; For a Plant is never known to be poisoned by its own natural Soil, nor starved, if it were enough of it, with the requisite Quantities of Heat and Moisture.

Roots, being therefore the Guts of Plants, have no need to be guarded by Senses; and all the Parts and Passages, which serve to distinguish and prepare the Food of Animals, before it reach the Guts, are omitted in Plants, and not at all necessary to them.

But as the Food of most Animals is Earth, very variously changed and modified by vegetable or animal Vessels, or by both, and some of it is made wholsome, some poisonous; so that if this doubtful Food should be committed to the Intestines, without Examination, as the pure unaltered Earth is to Roots, there would, in all Probability, be very few Animals living in the World, except there be any that feed on Earth at first Hand only, as Plants do.

Therefore, lest this Food, so much more refined than that of Plants, should, by that very means, become a fatal Curse, instead of a Blessing to Animals, Nature has endowed them with Smell and Taste, as Sentinels, without whose Scrutiny these various uncertain Ingredients are not admitted to come where they can enter the Lacteals, and to distinguish, at a sufficient Distance, what is wholsome and friendly, from what is hurtful; for when ’tis once passed out of the Stomach into the Guts, ’tis too late to have Benefit from Emetics; its Venom must then be imbibed by the Lacteal Mouths, and mix with the Blood, as that must mix with the Sap, which comes in Contact with the Lacteals in the Superficies of Roots, Nature having left this unguarded.

Yet Plants seem to be better secured by the Salubrity and Simplicity of their Food, than Animals are by their Senses: To compensate that Inequality of Danger; Animals have Pleasure from their Senses, except some miserable Animals (and such there are) that have more Pain than Pleasure from them. But I suppose, more Animals than Plants are poison’d; and that a poisonous Animal is less fatal to a Plant, than a poisonous Plant is to an Animal.

It being sufficiently proved, that every sort of Vegetables, growing in the same Soil, takes, and is nourished, by the same Sort of Food; it follows from hence, that the beneficial Change of Sorts of Seeds or Plants, we see in the common Husbandry, is not from the Quality of the Sorts of Food, but from other Causes; such as,

In Dr. Woodward’s Case, upon his Hypothesis, the Three Proportions of Seeds, viz. Barley, Oats, and Pease, might be sown all together in the same Acre of Ground, the same Year, and make Three as good Crops as if sown singly in Three successive Years, and his Two Crops of Wheat in one Year likewise. But every Farmer can tell, that these Three Proportions of Seed would not yield half the Crop together, as one would do single; and would scarce produce more than to shew what Grains were sown, and which, of the Sorts were the strongest and the most able Robber.

Though this Failure would, in Truth, be from no other Cause than want of the sufficient Quantity of Food, which those Three Crops required; yet, perhaps, the Doctor might think, that all Three Crops might succeed together very well, taking each its proper Nourishment, were it not for want of Room, Air, and Sun.

I have been credibly inform’d, that on One Perch of Ground there has grown a Bushel of Corn, which is Twenty Quarters to an Acre. Mr. Houghton relates Twenty-six, and even Thirty Quarters, of Wheat on One Acre. There have certainly grown Twelve Quarters of Barley to an Acre, throughout a whole Field: Therefore, unless a Crop exceed the least of these, or indeed the greatest of them (if the Relation be true), a Crop cannot fail for want of Room; for one Acre (be it of what Nature it will, as to the Soil of it) must have as much room for a Crop to grow on, as any other Acre.

Then there was room for all Dr. Woodward’s Three Crops together, to produce as much as Three common Crops do. Yet all these together will scarce yield one Quarter of Corn, tho’ there is room, at least, for Twelve.

The same Air and Sun that had Room to do their Office to Mr. Houghton’s Acre, why should they not have Room to do the same to Doctor Woodward’s Acre, when the Three Crops growing on it at once, through pretty good ones, might require less Room than Mr. Houghton’s Crop did?

I perceive that those Authors, who explain Vegetation, by saying the Earth imbibes certain Qualities from the Air, and by specific Qualities, and the like, do also lay a great Stress upon the perpendicular Growth of Vegetables; seeming to fansy there is little else necessary to a good Crop, but Room.

Mr. Bradley, in his Arguments concerning the Value of an Hill, does implicitly say as much.

But if they would but consider the Diameters of the Stems, with the Measure of the Surface of an Acre, they would be convinced, that many, even of Mr. Houghton’s Crops, might stand in a perpendicular Posture upon an Acre, and Room be left.

One true Cause of a Crop’s failing, is want of a Quantity of Food to maintain the Quantity of Vegetables, which the Food should nourish.

When the Quantity of Food which is sufficient for another Species (that requires less), but not for that which last grew, to grow again the next Year, then that other is beneficial to be planted after it.

The Second true Cause is from the Constitution of Plants; some require more Food than others, and some are of a stronger Make, and better able to penetrate the Earth, and forage for themselves.

Therefore Oats may succeed a Crop of Wheat on strong Land, with once plowing, when Barley will not; because Barley is not so well able to penetrate as Oats, or Beans, or Pease, are.

So a Pear-tree may succeed a Plum-tree, when another Plum-tree cannot; because a Pear is a much stronger Tree, and grows to a much greater Bulk; so inclined to be a Giant, that ’tis hard to make it a Dwarf; and will penetrate and force its Way thro’ the untill’d Earth, where the other cannot; being of a weaker and less robust Constitution, not so well able to shift for itself.

The Pear could penetrate Pores, that the other could not. Mr. Evelyn says, in his Discourse of Forest-trees, ‘That a Pear will strike Root thro’ the roughest and most impenetrable Rocks and Clifts of Stone itself.’ He says likewise, in his Pomona, ‘That Pears will thrive where neither Apple or other Fruit could in Appearance be expected.’

I can scarce think, that a large Plant takes in larger Particles than a small one, for its Nourishment: If it did, I can’t believe, that the Thyme could have starv’d the Apricot-tree; it must have left the larger Particles of Food for that Tree, which probably would have sufficed to keep it alive: I rather think, that great and small Plants are sustain’d by the same minute Particles; for, as the fine Particles of Oats will nourish an Ox, so they will nourish a Tom-tit, or a Mite.

Some Plants are of an hotter Constitution, and have a quicker Digestion, like Cormorants or Pigeons, devouring more greedily, and a greater Quantity of Food, than those of a colder Temperature, of equal Bulk, whose Sap, having a more languid Motion, in proportion to the less Degree of Heat in it, sends off fewer Recrements; and therefore a less Supply of Food is required in their room. This may make some Difference in the one’s succeeding the other; because the hot-constitution’d leaves not enough for its own Species to succeed again, but leaves enough for a Species of a colder Constitution to succeed it.

But the Third and chiefest Cause of the Benefit of changing Sorts is Quantity of Tillage, in proportion to which the Food will be produced.

The true Cause why Wheat is not (especially on any strong Soil) to be sown immediately after Wheat, is, That the first Wheat standing almost a Year on the Ground, by which it must grow harder; and Wheat Seed-time being soon after Harvest in England, there is not Space of Time to till the Land so much as a second Crop of Wheat requires.

Tho’ sometimes in poorer Land, that is lighter, Wheat has succeeded Wheat with tolerable Success; when I have seen, on very rich strong Land, the first Crop lost by being much too big, and one following it immediately, quite lost by the Poorness of it, and not worth cutting.

This was enough to satisfy, that the Tillage which was so much easier perform’d in less Time, sufficed for the light Land, but not for the strong: and, if the strong Land could have been brought into as good Tilth as the light (like as in the new Husbandry it may), it would have produced a much better second Crop than the light Land did.

From all that has been said, these may be laid down as Maxims; viz. That the same Quantity of Tillage will produce the same Quantity of Food in the same Land[209]; and that the same Quantity of Food will maintain the same Quantity of Vegetables.

’Tis seen, that the same Sort of Weeds, which once come naturally in a Soil, if suffer’d to grow, will always prosper in proportion to the Tillage and Manure bestow’d upon it, without any Change. And so are all manner of Plants, that have been yet try’d by the new Husbandry, seen to do.

A Vineyard, if not tilled, will soon decay, even in rich Ground, as may be seen in those in France, lying intermingled as our Lands do in common Fields. Those Lands of Vines, which by reason of some Law-suit depending about the Property of them, or otherwise, lie a Year or two untilled, produce no Grapes, send out no Shoots hardly: the Leaves look yellow, and seem dead, in Comparison of those on each Side of them; which, being tilled, are full of Fruit, send out an hundred times more Wood, and their Leaves are large and flourishing; and continue to do the same annually for Ages, if the Plough or Hoe do not neglect them.

No Change of Sorts is needful in them, if the same annual Quantity of Tillage (which appears to provide the same annual Quantity of Food) be continued to the Vines.

But what in the Vineyards proves this Thesis most fully is, That where they constantly till the low Vines with the Plough, which is almost the same with the Hoe-plough, the Stems are planted about Four Feet asunder, chequerwise; so that they plow them Four ways. When any of these Plants happen to die, new ones are immediately planted in their room, and exactly in the Points or Angles where the other have rotted; else, if planted out of those Angles, they would stand in the Way of the Plough: These young Vines, I say, so planted in the very Graves, as it were, of their Predecessors, grow, thrive, and prosper well, the Soil being thus constantly tilled: And if a Plum-tree, or any other Plant, had such Tillage, it might as well succeed one of its own Species, as those Vines do.

’Tis observed, that White-thorns will not prosper, set in the Gaps of a White thorn Hedge: But I have seen the Banks of such Gaps dug and thrown down one Summer, and made up again, and White-thorns there replanted the following Winter, with good Success.

But note, That the annual plowing the Vines is more beneficial than the one Summer Tillage of the Banks, the Vines having it repeated to them yearly.

I have, by Experience and Observation, found it to be a Rule, That long Tap-rooted Plants, as Clover and St. Foin, will not succeed immediately after those of their own or any other Species of long Tap-roots, so well as after horizontal-rooted Plants; but, on the contrary, horizontal will succeed those Tap-roots as well or better than they will succeed horizontal.

I confess, this Observation did, for a great while, cheat me into the common Belief, That different Species of Plants feed on different Food; till I was delivered from that Error, by taking Notice, that those Tap-roots would thrive exceedingly well after Turneps, which have also pretty long Tap-roots, though Turneps never thrive well immediately after Clover[210], or St. Foin: I found the true Cause of this Exception to that Rule to be chiefly the different Tillage[211].

Land must be well tilled for Turneps, which also are commonly hoed; they stand scarce ever above Three-quarters of a Year, and are then fed on the Ground; and then the succeeding Crop of Corn has, by that means, the Benefit of twice as much Tillage from the Hoe, as otherwise would be given to it; and the Broad Clover, or St. Foin, sown with the Corn (if the Corn be not so big as to kill it), will enjoy, in its Turn, a Proportion of the extraordinary Tillage, and of the Dung of Cattle, which feed the Turneps, and thrive accordingly: But Broad Clover and St. Foin, being perennial Plants, stand on the Ground so long, that it lies several Years untilled; so that Turneps, sown immediately after these, do fail, for want of their due Tillage, for which there is not sufficient time, by plowing often enough; because, by the common Ploughs, it requires Two or Three Years to make it fine enough for Turneps, or for a Repetition of Clover, or St. Foin, in strong or swerdy Land.

Another Reason why any Crop succeeds well after Turneps (and besides their being spent on the Ground where they grow) is their cold Constitution, by which they are maintained with less Food than another Plant of the same Bulk.

The Parenchyma, or fleshy Part of a Turnep, consisting of a watry Substance, which cools the Vessels, whereby the Sap’s Motion is very slow, in proportion to the very low Degree of Heat it has, and sends off its Recrements in the same Proportion likewise; and therefore requires the less of the terrene Nourishment to supply those Recrements.

This is seen, when a Bushel of Turneps, mixed with a Quantity of Wheaten Flour, is made into Bread, and well baked: This Bushel of Turneps gives but few Ounces Increase in Weight, more than the same Quantity of Wheaten Flour made into Bread, and baked without any Turneps. This shews there is in a Turnep very little Earth (which is the most permanent Substance of a Plant); the Oven discharges in Vapour near all but the largest Vessels: Its earthly Substance being so small, is a Proof ’tis maintained by a small Quantity of Earth: and, upon that Account also, of less Damage to the next Crop than another Plant would be, which required more of the solid Nourishment to constitute its firmer Body, as a Charlock does; for when a Charlock comes up, contiguous to, and at the same time with a Turnep, it does so rob the Turnep, that it attains not to be of the Weight of Five Ounces; when a single Turnep, having no more Scope of Ground, and, in all respects (but the Vicinity of the Charlock), equal, weighs Five Pounds, yet that Charlock does not weigh One Pound.

And where Three Turneps coming up, and growing thus contiguous, will weigh Four Pounds; a Charlock joined with Two or Three Turneps, all together, will be less than one Pound, upon no less Space of Ground.

This Observation cannot be made, except where Turneps are drilled in Rows; and there ’tis easy to demonstrate, that a Charlock, during the time of its short Life, draws much more Earth than a Turnep of equal Bulk, from an equal Quantity of Ground[212].

The true Cause why Clover and St. Foin do not succeed so well after their own respective Species, or that of each other, as Corn, &c. can, is, that they take great Part of their Nourishment from below the Plough’s Reach, so as that under Earth cannot be tilled deep enough, but the upper Part may be tilled deep enough for the horizontal Roots of Corn, &c. towards which, the Rotting of the Clover and St. Foin Roots, when cut off by the Plough, do not a little contribute[213]; And there’s no doubt but that, if the under Earth could be as well tilled for the Tap-roots, as the upper Earth is for the horizontal, the Tap-roots would succeed one another as well as the horizontal would succeed them, or those of their own Species, or as the Tap-roots do the horizontal.