|The following Five Chapters have been formerly published as a Specimen.|
|CHAPTER XVI. |
Of CHANGE OF SPECIES.
II That there is no plant but what must rob any other plant within its reach.
III. That a soil which is proper to one sort of vegetable, once, is, in respect of the sort of food it gives, proper to it always.
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, though falsely, supposed to yield*.
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** to this art, has unhappily fallen in with the vulgar in this point, his arguments for this error require to be answered in the first place.
* For if all plants robe one another, it must be because they all feed on the same sort of food ; and admitting they do, there can be no necessity of changing the species of them from one soil to another ; but the same quantity of the same food, with the same heat and moisture which maintains any species one year, must do it any other year.
** By proving in his Experiments, that earth is the pabulum of plants.
The Doctor says*, " It is not impossible 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. It is very probable, that the terrestrial particles which constitute vegetables, though 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 smallness 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 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 that is capable of entering its roots**.) Though the terrestrial particles which nourish vegetables be not perfectly homogeneous, yet most of the various tastes and
* In Philos. Trans. N. 253.
** Dr. Grew, in his anatomy of plants by microscopical inspection, found, that the outer superficies of roots was of a spongy substance ; and it is well known that no such body can refuse to imbibe whatever liquor comes in contact with it, but will be its springy porosity absorb any sort of moisture.
flavours of plants are made in and by the vessels*.
Dr. 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 it is endowed with for the purpose, intercepts and assumes into itself such particles as are suitable to its own nature**, 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
* We are convinced that it is the vessels of plants that make the different flavours ; because there is none of these flavours in the earth of which they are made, until that has entered and been altered by the vegetable vessels.
** If the Doctor's plants were so nice in leaving vegetable matter behind, quiet and undisturbed, it is a wonder they would take up the mineral matter, as he says they did that killed themselves with nitre.
These plants might with much less difficulty have distinguished the mineral matter from the vegetable matter, than they could distinguish the different particles of vegetable matter from one another, and must have been very unwise to choose out the nitre (their poison) from the water and earth, and to leave the vegetable particles behind ; none of which could be so improper to them as the nitre.
It may, perhaps, be objected, that such like pernicious matter kills a plant by only destroying its roots, and by closing the pores, which prevents the nourishment from entering to maintain its life ; and that such matter doth not itself enter to act as poison upon the sap, or upon the vessels of the body, or leaves : but it plainly appears that it doth enter, and act as poison ; for when some of the roots of a mint, growing in water, are put into salt water, it kills the whole plant, although the rest of the roots remaining in the fresh water were sufficient to maintain it, if the other roots had been cut off at the time they were removed into the salt water ; and also all the leaves, when dead, will be full of salt.
Or if the juice of wild garlic-seed be made use of instead of the salt water, it will have the same effect ; and every one of the mint leaves will have a strong taste of garlic in it.
for its augment, and the unsuitable lets pass through it. And in another place, he says, they are exhaled 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 undisturbed the while. And when the earth has yielded up all of them, those that are proper for barley, a different gain, remain still behind, till the successive crops of that corn fetch them forth too ; and so the oats and peas in their turn, till, in time, 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.
Query, Whether Equivocus's allowing, that the same nourishment is common to all plants, and proper to none ; and yet affirming the necessity of changing the species of plants on account of the quality of the nourishment, doth not in effect grant the premises, and deny the conclusion ?
If in this series of crops each sort was 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, peas, and oats, instead of being sown before the, and then it would evidently appear by that starved 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*
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 worse 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 cleared, could we perfectly know the nature of those supposed unsuitable** particles ; but, in truth,
*A charlock could not rob a turnip and starve it more than several turnips can do, unless the charlock did take from it the same particles which would nourish a turnip ; and unless the charlock did devour a greater quantity of that nourishment than several turnips could take.
Flax, oats, and poppy, could not burn or waste the soil, and make it less able to produce succeeding crops of different species, unless they did exhaust the same particles which would have nourished plants of different species ; for, let the quantity of particles these burners take be never so great, the following crops would not miss them, or suffer any damage by the want or loss of them, were they not the same particles which would have nourished those crops if the burners had left them behind, quiet and undisturbed. Neither could weeds be of any prejudice to corn, if they id draw off those particles only that suit the bodies of weeds, the rest lying all quiet and undisturbed the while. But constant experience shows, that all sorts of weeds, more or less, diminish the crop of corn.
** But we must not conclude that these particles, which pass through a plant (being a vastly greater quantity than those that abide in it for its augment) are all unsuitable, because no one of them happens to hit upon a fit nidus : for since the life of animals depends upon that of plants, it is not unreasonable to imagine that nature may have provided a considerable overplus for maintaining the life of individual plants, when she has provided such an innumerable overplus for continuing every species of animals.
there is no more to be known of such of them, than that they are carried away by the atmosphere to a distance, accounting to the velocity of the air, perhaps several miles off, at least never likely to return to the spot of ground from whence the plants have raised them.
But suppose those cast-of particles, were, when taken in, unfit for the nourishment of any manner of vegetables : then the Doctor must fancy 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, peas,and oats, letting that lie still and undisturbed the while, as he says it does, though he gives no manner of reason for it.
It is 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 undisturbed the while."
There are, doubtless, more than a million 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 supplied 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 remained 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 quite the contrary appeared. " 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 nubeculę diffused through the body of the water thicker." Had the cataputia insumed 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 kinds 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 stamped 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 Doctor Wallis) to decipher the language of plants from invisible characters.
Dr. Woodward seems to have had as good eyes and as strong an imagination as the old woman who saw the needle upon the barn but could not see the barn.
I will by no means call in question the veracity of so learned and good a man, and therefore am willing to believe he made this extraordinary observation in his sleep.
I am reproached by Equivocus for insulting the ashes of this gentleman, but in truth he was living when I wrote this Chapter ; I am sure I believed so : and I hope what I have written can no way reflect upon the Doctor's memory, but as he was a man, and liable to be deceived by too great a zeal for a favourite hypothesis, which sometimes makes one imagine one sees a thing that has no real existence. This observation of the Doctor's, as he expresses it, seeming to have been made by inspection upon a glass of water with earth in it, for the discovery of all the different sorts of particles in that earth ; if I had contradicted the result of his observation concerning the " vegetable matter, consisting of very different particles, some of which (the Doctor says) are proper for the nourishment of some kinds of plants, others for different sorts, &c.;" as to the fact related from a clear ocular inspection, it might have reflected more on the Doctor's ingenuity, than to impute it, as I have, to the effect of mere imagination, seduced by zeal for his hypothesis.
However, at the worst, I presume the refuting and exposing an error so injurious to mankind, may atone for an expression or two in my arguments thereupon, which are not injurious to the probity or veracity of him who advanced that error, but that are rather an excuse for his mistake ; and if Equivocus speaks true, when he saith that Columella's first Essay was written to ridicule an error of his contemporaries, why should not an error so fundamental as this be ridiculed now, since its being shown to be ridiculous is an
argument that weighs more with many husbandmen, than demonstration ? And I think that no argument consistent with truth, should be omitted, which can any way conduce to the establishing a principle that is essential towards treating of agriculture as a science.
But that this dream may deceive none, except such as are very fond of old errors, there is an experimentum crucis which may convince them, viz., at the proper season, tap a birchtree 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 confined 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 honogenial 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 it is 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.
Certainly no mortal, except Doctor Woodward, can pretend to distinguish the particles of vegetable matter by any characters, hieroglyphics, or other manner whatever, so as to determine to what species, or class of plants, they are severally proper and peculiar ; neither is it probable, that any botanist is acquainted with half the distinct species of vegetables. Yet all the vegetable particles, and all the species of vegetables, must be perfectly and distinctly known by water, before it be capable of performing such a nice task of an agent ; else, when wheat, barley, and oats, are all growing together, in the same foot of ground, with their roots so entangled together, that no man can possibly distinguish the one from the other, by viewing the roots how should this insensible agent be punctual in delivering to each its own proper particles ? For, though the agent had most exactly executed a commission of disturbing the inactivity of these three sorts of particles only ; yet, when it had fetched them forth, if it should err in the delivery of them, and carry the wheat-particles to the barley, and those of barley to the oats, it would be a mistake of worse consequence, according to the Doctor's opinion, than that of the London undertaker's, who being to inter an old man in Northumberland, and a young lady in Cornwall, carried the man to Cornwall, and the lady to Northumberland. Her mother, for mitigation of grief, would not be satisfied without a last sight of her daughter's corpse ; but, when
the coffin was opened, the error was discovered by the indubitable criterion of an old shrivelled face, with a huge grey beard. It is no real injury to a person deceased, if the place of his burial be mistaken ; but if water should mistake thus in the taking up, carrying, and delivery of vegetable particles, all plants would be (upon the Doctor's hypothesis) starved or poisoned, and animals could not long survive all plants. But since all the different species of plants do continue to live, their life proves, that the vegetable particles of earth are not proper, but common to them all for their nourishment, if these particles are taken up, carried, and introduced into the vegetable vessels by water ; which is capable of distinguishing neither different vegetable particles, nor different vegetables.
Since it is 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 roots 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 introduced and advanced 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 endowed with.
Mr. Bradley seems to have carried this error further than any author ever did before ; but he supports it be 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, refusing 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, helps 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 robbed the apricot-tree of so much of its share as to starve it ; and that they, though 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 mints G. and HH., 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.
Some of the Anticircularians (but Mr. Bradley was not one) may
believe, that the chyle is altered and made into sap in the roots ; but the experiment of my mint (G) will show that no such alteration is made in the roots.
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 it is 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 filtered, &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, though all draw their nourishment from the same stock lodged in the earth." See Mr. Bradly'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, it is 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 toward 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 mouth 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 wholesome, 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 wholesome and friendly, from what is hurtful ; for when it is once passed out of the stomach into the guts, it is 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.
The nutriment, or chyle, that a root takes in, must mix with the sap in the leaves, unless some of it happens to pass out at other roots in the manner described in my note upon Circulation.
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 that pleasure from them. But, I suppose, more animals than plants are poisoned ; and that a poisonous animals is less fatal to a plant, than a poisonous plant is to an animal. An instance of this - I have been told, by very credible persons, that a man walking in a garden, gathered a spring of sage, and eat it, which soon brought upon him the symptoms of poison and death. They dug up the root of sage, and found a toad under it.
Some of the effluvia or excrementitious juices of this loathsome animal had passed the vessels of that wholesome plant, without any apparent injury to it, though all its strainers were not able to correct the venom.
Here I remark that the mint (E) suffered more pestiferous effects from the garlic, of its own genus, than the sage did from the toad, though of a different genus.
It killed the man, but was not strong enough to kill the sage. This shows that plants have not occasion of palates, as animals have.
I say no more of Mr. Bradley's vegetable palates ; I proceed to some other arguments against the necessity of changing sorts of vegetables, on account of their taking different nourishment.
It being sufficiently proved, that every sort of vegetable, 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,
I. Quantity of the food.
II. Constitution of the plants.
III. Quantity of the tillage.
In Dr. Woodward's case upon this hypothesis, the three proportions of seeds, viz., barley, oats, and peas, may 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 what 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 show 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 informed, 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 has 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, though 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 Dr. Woodward's acre, when the three crops growing on it at once,
though 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 fancy there is little else necessary to a good crop, but room.
Mr. Bradley, in his arguments concerning the value of a 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 ploughing, when barley will not ; because barley is not so well able to penetrate as oats, or beans, or peas 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 it is hard to make it a dwarf ; and will penetrate and force its way through the untilled 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 through 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 cannot believe, that the thyme could have starved 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 sustained by the same minute particles ; for as the fine particles of oats will nourish an ox, so they will nourish a tomtit, or a mite.
Some plants are of a 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 succeeding the other ; because the hot-constutioned 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 chief 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.
Though 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 be 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 performed 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, here may be laid down as maxims, viz., that the same quantity of tillage will produce the same quantity of food in the same land ; and that the same quantity of food will maintain the same quantity of vegetables.
Add cęteris paribus ; for when the land has been more exhausted, more tillage (or dung) or rest will be required to produce the same quantity of food, than when the land hath been less exhausted. By tillage is here meant, not only the number of ploughings, but the degree of division or pulverisation of the soil ; or if perchance the soil is extraordinarily much exhausted by many crops without proper tillage between them, the greater degree of pulverisation, by ploughing or dung (which is only a succedaneum of tillage), and also a longer time of exposure may be necessary to counterpoise that extraordinary exhaustion.
It is seen, that the same sort of weeds which once come naturally in a soil, if suffered to grow, will always prosper in proportion to the tillage and manure bestowed upon it, without any change. (And so are all manner of plants that have been yet tried by the new husbandry, seen to do.)
A vineyard, if not tilled, will soon decay, even in rich ground, as may be seen by 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 a hundred times more wood, and their leaves are large and
flourishing ; and continue 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, chequer-wise ; so that they plough 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 others 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 predecessor, 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.
It is 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 ploughing 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 wasdelivered from that error, by taking notice, that those tap-roots would thrive exceedingly well after turnips, which have also pretty long tap-roots, though turnips never thrive well immediately after clover or St.-Foin ; I found the true cause of this exception to that rule, to be chiefly the different tillage*.
But when clover hath been fed by cattle, and the ground being good and well tilled, turnips may thrive immediately after clover ; therefore this is an exception to the general rule.
Land must be well tilled for turnips, 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 turnips, 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 turnips
* Very mellow, rich land is so full of vegetable food, that it is an exception to most rules ; and therefore I speak not of that.
sown immediately after these, do fail, for want of their due tillage, for which there is not sufficient time, by ploughing often enough, because, by the common ploughs, it requires two or three years to make it fine enough for turnips, or for a repetition of clover or St.-Foin, in strong or swerdy land.
Another reason why any crop succeeds well after turnips (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 turnip, consisting of a watery substance, which cools the vessels, whereby the sap's motion is very slow, in proportion to the very low degree of heat it as, and sends off its recrements in the same proportion likewise ; and therefore requires the less of the terrene nourishment to supply those recrements.
A turnip, it is like, has larger chyle-vessels in proportion to its sap-vessels, than many other sorts of plants have ; and the greatest part of this chyle being water, it may well be supposed colder than sap.
This is seen when a bushel of turnips, mixed with a quantity of wheaten flour, is made into bread, and well baked ; this bushel of turnips gives but few ounces increase in weight, more than the same quantity of wheaten flour made into bread, and baked without any turnips. This shows there is in a turnip very little earth (which is the most permanent substance of a plant), the oven discharges, in vapour, near all but the largest vessels ; its earthy substance being so small, is a proof it is 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 turnip, it does so rob the turnip, that it attains not to be of the weight of five ounces ; when a single turnip, having no more scope of ground, and in all respects (but the vicinity of the charlock) equal, weights five pounds, yet that charlock does not weigh one pound.
And where three turnips coming up, and growing thus contiguous, will weigh four pounds, a charlock joined with two or three turnips, all together will be less than one pound, upon no less space of ground.
This observation cannot be made except where turnips are drilled in rows ; and there it is easy to demonstrate, that a charlock, during the time of its short life, draws much more earth than a turnip of equal bulk, from an equal quantity of ground*.
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. And there is doubt but than, if the under-earth could
* It is certain that turnips, when they stand for seed, suck and impoverish the ground exceedingly ; for though they are of a cold constitution, and consequently consume less food than plants of a hotter constitution, and of the same bulk, yet, these seed-turnips being so vast a bulk, as sometimes eighty quarters of their roots grow on an acre, and their stalks have been measured seven feet high ; and the roots having continued at near their full bigness, for about ten months together, and then carried off, they drain the land more than a crop of other vegetables of less bulk and a hotter constitution, which live a less time ; or than wheat, which, though it lives as long, is very small, except in the four last months.
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.
That the rotting of vegetable roots in the ground doth ferment therein, and improve it for horizontal-rooted plants, I am convinced by an accident, viz., my man had ploughed off the earth close to the rows in a field of extraordinary large turnips designed for seed. This earth was neglected to be thrown back to the rows until a severe frost in the winter came and killed the turnips ; upon which, in the spring the field was sown with barley upon the level with only once ploughing, and that crosswise of the rows. The turnips had stood so wide asunder, that the sport whereon each had rotted appeared like the sport whereon a horse had urined in tilled ground, and was of a deeper colour and much higher than the barley that grew round those spots, and yet none of it was poor. As the roots of clover and St.-Foin are very much less, yet the greater number rotting in ploughed ground must be of great use to a following crop of corn.
I will here relate two examples of this in St.-Foin ; the one is, that a field of twenty-five acres drilled with St.-Foin except three acres in the middle of it, which was at the same time sown with hop-clover ; after eight years the whole field was plowed up by a tenant, and sown with corn : the St.-Foin had been mowed yearly as the hop-clover was not mowed at all, but fed by horses teddered (or staked) thereon the first and second years, and after that had nothing on it but poor natural grass.
The whole field was managed alike when ploughed up ; but the three acres produced visibly worse crops of corn than the rest all round it, which had produced St.-Foin.
The other example, or instance, was, where an acre, part of a field, was, by a fancy, drilled with St.-Foin in single rows, about 33 inches asunder, but was never hoed : after seven years it was ploughed up with the rest of the filed across the rows, and sown with oats upon the back three months after ploughing. These rows were as visible in the oats as if the St.-Foin has been still remaining there. The oats in the rows where the St.-Foin had been, looked of a deep green flourishing colour at first coming up, and until they were about half a foot high, and the spaces between them looked yellowish ; but afterwards the difference of their colour disappeared, all the crop being very good. Upon this I imputed it tothe rotting of the roots, which by their singleness were very large ; and when the different colours disappeared, I suppose the roots of all the oats had reached to the benefit of the rotted roots, which might also be then spread further into the spaces, and I doubt not but that the rotting of broad clover-roots has the same effect as of St.-Foin, for manuring of land, especially when the roots are large.
The under-earth, in some time, is replenished by what the rains leave, when they sink through it ; and then tap-rooted plants may be there nourished again, though the upper-earth be drained by the corn ; so that no change is so beneficial, as that betwixt tap-rooted plants, and those which have only horizontal ones. The former are provided for by rains, though not so speedily as the latter are by tillage and hoeing.
Pasture requires no change of herbs ; because they have annually the same supply of food from the dunging of cattle that feed on them, and from the benefit of the atmosphere.
Meadows hold out without change of species of grass, though a crop be carried off every year ; the richness of that soil with the help of the atmosphere, dung of cattle in feeding the after-crop, or
else flooding, from the overflowing of some river, some, or all of which, supply the place of the plough to a meadow.
Woods also hold out beyond memory or tradition, without changing sorts of trees ; and this by the leaves, and perhaps, old wood rotting on the soil annually, which operate as a manure, because, as has been said, earth which has once passed any vessels, is so changed, that for a long time after it does not regain its homogeneity* so much as to mix with pure earth, without fermenting ; and by the descent of the atmosphere, the trees shadowing the soil, to prevent
* Not that the particles of earth are strictly homogeneous, but that they are much less heterogeneous before they are altered by vessels, than afterwards.the re-ascent of what that brings down ; all this resembling tillage, continually divides the soil, and renews the food equal to the consumption of it made by the wood.
And the last argument I shall attempt to bring for confirmation of all I have advanced, is, that which proves the truth and use of the rest, viz., that when any sort of vegetable, by the due degrees of heat and moisture it requires, is agreeable to a soil, it may, by the new horse-hoeing husbandry, be continued without every changing the species.