Читать книгу: «The Romance of Plant Life», страница 18
CHAPTER XXI
STORY OF THE CROPS
Bloated and unhealthy plants – Oats of the Borderers, Norsemen, and Danes – Wheat as a wild plant – Barley – Rye – Where was the very first harvest? – Vine in the Caucasus – Indians sowing corn – Early weeds – Where did weeds live before cultivation? – Armies of weeds – Their cunning and ingenuity – Gardeners' feats – The Ideal Bean – Diseased pineapples – Raising beetroot and carrot – Story of the travels of Sugar-cane – Indian Cupid – Beetroot and Napoleon.
IT is difficult to understand the amount of labour and toil that has been spent on farmlands and pastures, if one only considers England.
It is often impossible to discover one square mile still covered by the natural wild plants. It is all under corn or arable, or rich artificial meadowland.
But from a Scotch hillside, as one looks down at the fertile valley below, one can see first where the mosaic of hedges and dykes stops, then where, after a narrow stretch of rough grass pasture, the cultivation ends; finally, where, ridge after ridge, rolling, heathery moorland, without enclosures and without any sign of man's handiwork, rises up to the highest peaks.
This fills one with a respect and reverence towards our forbears, which is increased by a study of corn, turnips, and potatoes.
Every one of these plants is a thoroughly unnatural, artificially bloated, and overfed sort of creature. Its constitution, as is usual with those who habitually overeat themselves, is delicate and unsound.
No cultivated plant could exist for more than a season if man did not look after it and protect it from its rivals and weeds. Moreover, they are a curiously assorted lot.
Wheat probably came from Asia Minor, Swedes from Scandinavia, Mangelwurzel from the Mediterranean, and Potatoes from Chile. Turnips and Carrots are indeed native Britishers, though the original wild carrot or turnip would never be recognized as such by any ordinary person.
The history of every one of them is interesting. The Oat is the true Teutonic and Scandinavian grain, which has more "fibre" than any other cereal. There is an interesting passage in Froissart's Chronicles describing the commissariat of those hardy Scotch borderers who raided and ruined the northern English counties whenever they felt inclined to do so.120 They lived for the most part on the cattle of their enemies, but each man carried a small sack of oatmeal and a griddle, or iron plate, on which to make oatcake. So that each man supported himself. His little rough pony also was quite able to look after itself.
That hardy plant, the Oat (Avena sativa) can be cultivated as far north as 69.50° N. lat. It is a native of Siberia and Western Europe.
It was oatmeal that supported the Norsemen who conquered Normandy and England, and who even dominated the Mediterranean. The Swedes of Gustavus Adolphus and the Danes of Canute also lived mainly upon oatmeal and porridge. It is true that in England oats are abandoned to the horses, but those horses are the best in the world. There can, of course, be no question as to whether the Scotch or English are the best!
The history of Wheat is a very complicated one; there are a great number of varieties and sub-species, all closely allied to our ordinary wheat, and difficult to distinguish from it. One variety occurs as a wild plant from Mesopotamia, near Ararat, over Servia, the Crimea, and as far as Thessaly, where entire hills are covered by it. This grain seems to have been cultivated at Troy, for Dr. Schliemann has found it at Hissarlik. It was, however, in cultivation long before the days of Achilles; it was grown by the Stone Age people, who lived in the lake dwellings of Switzerland. Another kind, "spelt" wheat, seems to have been the mainstay in ancient Egypt, in Greece, and all through the Roman Empire. It is now very rare, though it is still grown in Spain and in other countries where the soil is poor.
Grains of the true Wheat have been discovered in the Pyramids of Egypt, so that it also is very ancient. To-day Wheat extends to Norway (69° N. lat.), and may be grown up to 4400 feet on the Alps.121 India, United States, Russia, the Argentine, Chile, Australia, and many other countries, produce great crops of this useful and nourishing food. Its fibre is 3 per cent., albuminous matter 11-1/2 per cent., and carbo-hydrates 66·5 per cent. Oat has 10 per cent. fibre, 11-1/2 per cent. albuminous, and 57 per cent. carbo-hydrates.
One guess as to the origin of Wheat is that the first-named (Mesopotamian sort) is the original wild plant. By cultivation in the rich alluvial valleys of Mesopotamia and Egypt, improved kinds were formed. These have eventually replaced both "spelt" wheat and the wild race, but could only do so when richly-cultivated fields were ready for them. On poor soil and with bad cultivation, "spelt" is said to be even now the most profitable crop.
Wild Barley grows in Arabia and from Asia Minor to Baluchistan. It is very important in the colder regions of Northern Europe, in Tibet, and in China, but with us "John Barleycorn" is chiefly used for brewing.
Rye also comes from Asia Minor. It was not apparently known in Europe until the Bronze period, but is now "the chief cereal of the German and Slavonic nations." The black rye-bread is familiar to all who have travelled on the Continent. The straw is good fodder, and is used for making hats and for paper.122
A very interesting point on which, however, it is quite impossible to come to a definite decision, may be noticed here. We will suppose what is quite as likely as any other theory, viz. that man as a gardening creature first settled somewhere in the Euphrates or Caucasian valleys.
What wild plants, then, would have been available for his experiments?
This particular region is an interesting and remarkable one. Most of our common British plants occur along the shore of the Black Sea to the Caucasus (apple, pear, nut, turnip, cabbage, carrot, and others, are all probably to be found there). On the Babylonian side of the mountains, there is a warm sub-tropical climate in which almost every useful plant can be grown. The desert also contains a few other valuable plants.
Near Ararat, Noah might have found rye, wheat, and barley growing wild. The Wild Vine also grows on the south of the Caucasus. "It grows there with the luxuriant wildness of a tropical creeper, clinging to tall trees and producing abundant fruit without pruning or cultivation."123 In that favoured district, the olive and the fig, the melon and cucumber, onions, garlic, and shallots, and other common garden and medicinal plants, can be found. Not far away is the native country of the camel, the ass, the horse, and most other domestic animals.
Were these hillsides of Ararat or thereabouts, the first place where man sowed and reaped a harvest?
At any rate, in those flat, fertile, alluvial plains of the Euphrates, and also in Egypt, the first great cities arose.
But even in the later Stone Age, which may have been about 58,000 B.C., some of these Caucasian plants seem to have been in cultivation in Switzerland. Probably every subsequent invasion, first that of races with bronze weapons, and then of others in the Iron Age, brought with it new cultivated plants.
The Oat seems to be an exception to the rule, for, so far as one can gather, it was not a native of Asia Minor.
The first harvest was, however, in all probability, a very casual and occasional kind of thing.
Mason (Origin of Inventions, page 192) has described such a kind of cultivation which was in existence amongst the American Indians quite recently. "A company of Cocopa or Mohave or Pima women set forth to a rich and favoured spot on the side of a cañon or rocky steep. They are guarded by a sufficient number of men from capture or molestation. Each woman has a little bag of gourd seed, and when the company reach their destination she proceeds to plant the seeds one by one in a rich cranny or crevice where the roots may have opportunity to hold, the sun may shine in, and the vines with their fruit may swing down as from a trellis. The planters then go home and take no further notice of their vines until they return in the autumn to gather the gourds" (E. Palmer).
There is an interesting point about the cultivation of those early savage peoples who built up for themselves unhealthy but elaborate wooden dwellings in the Swiss lakes, in order to escape wild beasts and human beings who were even more dangerous and ferocious than they.
Weeds occurred in those cornfields, cultivated by stone implements, some 60,000 years ago.
The seed of an Italian weed had been introduced with their corn, and was discovered in Switzerland!
Weeds are an extremely interesting group. A proverb about the hardiness and multiplication of weeds can be discovered in almost every language. "Ill weeds grow apace," Unkraut verbessert nicht, and so on. They are very common. In fact weeds, wayside, and freshwater plants, have by far the widest distribution of all. There are twenty-five species which can be found over at least half the entire land surface of the earth, and more than a hundred occupy a third of it.124
Moreover, many of our common weeds existed in Britain when the glaciers and ice melted away, and there were as yet no people able to cultivate the ground.
The Creeping Buttercup, Chickweed, Mint, Persicaria, Dock, and Sheep's Sorrel had already colonized the country, before the Great Ice Age came upon them, and at least fourteen weeds were here when the first corn-raising savages landed in Britain.125
At first sight it is difficult to understand where and how they lived. One discovers a very few, however, if one botanizes very carefully along the seashore, or on river banks where landslips have occurred, and in other such places where bare ground exists which is not the result of cultivation.
There these weeds fulfil a very important and useful purpose. The "red smear" of a landslip is soon tinted green with Coltsfoot, Chickweed and the like, and the bare earth, which was useless and supported no green covering, is very soon made once more a part of the earth's fruitful field. In such places the weeds are soon overcome and suppressed by the regular woods, grass, or thicket of the district.
It is far otherwise in arable land, where man desires to keep the ground bare in order to give his own domestic plants the best part of the soil.
Let us look for a little at what actually happens in an ordinary cornfield. It is not merely one generation of weeds, but whole armies, that the farmer has to contend with.
When the young corn is growing up (1) the bright yellow Charlock grows much more rapidly, and the whole cornfield is golden with it. The Charlock grows to some eighteen inches high, flowers, and sets its seed before it is suppressed by the growth of the cornstalks, which, of course, may be three or four feet or more in height.
(2) Another series of weeds, such as Spurrey, are growing in the shelter of the tall stalks, and their flowers are ripened and their seed scattered long before the corn is cut. (3) Another series, such as Polygonums, etc., become ripe and are about the length of the corn, so that when it is cut and thrashed the seed of the Polygonum accompanies the grain and is probably sown with it. (4) Then there are such weeds as the False Oat grass, etc., which are taller than the Oat, and whose seeds are blown off and scattered all over the field before the harvest. One would think that those exhausted the series, but far from it: the farmer cuts and carries the crop, and for two or three days the ground is almost bare, but if you revisit the field a week afterwards you can no longer see the ground. The cut-off yellow stalks of the corn are set off by a dark continuous green carpet of flourishing weeds. This last, (5) the "waiting division" of the weeds, remain quietly until the corn is removed and then get through their flowering and seeding before the field is ploughed up or covered by grass.
Now if one thinks for a little over the cunning and ingenuity of these proceedings, it is obvious that each single weed has somehow learnt how to develop exactly at the right time. Those especially which are intended (by themselves) to form part of the seed mixtures must flower exactly at the same time as the corn. As a matter of fact, most seed mixtures are often full of weeds. In a single pound of clover seed, no less than 14,400 foreign seeds, including those of forty-four different weeds, have been discovered.126
Others scattered on the ground will probably be buried and remain five to seven years below the surface, yet they are ready to come up flourishing as soon as they get a chance.
How has this been brought about? It is only since about 1780 to 1820 that our present system of farming has prevailed. In these 125 years, these weeds have found out exactly how to establish themselves.
The explanation is probably a very simple one. Every weed which did not bloom and seed exactly at the right time was killed and left no seed. This encouraged the others, who have gradually brought about the neat little arrangements above described. A process of selection has been at work. Those that would not modify their arrangements to suit new methods of farming have been suppressed.
But it is in some of the cultivated plants themselves that one sees the most extraordinary results of selection.
The Wild Cabbage is still to be found on sea-cliffs on the south-western coast of England, and the Wild Turnip occasionally occurs in fields. There is nothing particularly interesting or attractive about either of them.
Yet from the one has been produced cabbage, cauliflower, seakale, brussels sprouts, broccoli, and kohlrabi; and the other has given the endless varieties of turnips. For the most part these extraordinary changes have been brought about in a perfectly straightforward way, by just choosing the biggest and finest sorts for seed.
Some of the feats performed by gardeners in this way are almost incredible. A United States seedsman evolved the idea of a perfect bean from his inner consciousness. It had a particular shape which he described to a noted grower of beans. Two years later his ideal bean was produced!
The growers of pineapples used to have a great deal of difficulty on account of the pineapple cuttings becoming unhealthy. Sometimes 63 per cent. were more or less diseased. Then certain growers began to carefully select disease-proof pineapples, and finally reduced the percentage of diseased cuttings to four per cent. Another French observer (M. Roujon) by continually selecting the smallest seeds, was able to obtain corn only eight inches high.
But by far the most interesting and important researches have been those dealing with roots and tubers. Several people have, in fact, done in a few years what it took primitive man centuries to accomplish.
Thus, in 1890, E. v. Proskowetz obtained some seeds of the wild Sea-beetroot which is found on the south coast of France. By very careful selection he was able in the year 1894 to get good beetroots quite like the ordinary cultivated ones. These were biennials (not annuals like the wild plant), and had a large percentage of sugar – 16·99 per cent. This was by selection in good and fertile soil.127 Vilmorin also obtained quite good carrots in the fourth generation by cultivating the wild form in rich and good soil, and selecting the best.
In fact there are in natural wild plants great differences between individuals, and when such plants are cultivated in good soil, where they have far more to eat than they require, the result is that they produce extraordinary and monstrous types.
These types are, however, more or less delicate, and are weak in constitution and easily killed. To prevent such variations those who wish to keep a race of seed pure are careful to keep it growing on poor land.
In 1596 the Hyacinth (Hyacinthus orientalis) was introduced from the Levant. In 1597 there were four varieties, and in 1629 eight kinds were known, but in 1768 two thousand forms of hyacinth were named and described.
Besides selection, the method of hybridizing or crossing is often used in order to obtain new or valuable strains. Generally both hybridizing and crossing are employed. This method has long been practised. Bradley, in 1717, writes as follows: "A curious person may by this knowledge produce much rare kinds of plants as have not yet been heard of"; and, in fact, peaches, potatoes, plums, strawberries, and savoys have all been greatly improved by hybridizing and selection.128 By crossing certain kinds of corn, such as the Chinese Oat and the wild European Oat, varieties have been produced by Messrs. Garton which at the Highland and Agricultural Society's trials produced 84, 87, and 99 bushels per acre, as compared with 58 bushels yielded by the ordinary Scotch Oat.129 With potatoes also astonishing results have been got.
One single potato was sold for £50 not very long ago.
The Potato, like the Indian corn, tobacco, and a few other plants, is an inhabitant of the New World. Of other cultivated plants the native country is not known. No one knows where, for instance, Sugar-cane was first cultivated, but it has nine Sanskrit names, one of which, khand, is, or has probably at one time been familiar to us as sugar-candy. It was well-known when the Institutes of Manu were written, but that may have been somewhere between 2000 B.C. and A.D. 20.
One of the Hindu Indian deities, Kámadeva, who corresponds to Cupid, the God of Love, carries a bow made of sugar-cane, with a string which is composed of bees.
"He bends the luscious cane and twists the string
With bees: how sweet! but ah! how keen their sting,
He with five flowerets tips the ruthless darts
Which through five senses pierce enraptured hearts."
From India it seems to have been carried by Alexander the Great to Asia Minor, for it is mentioned by Herodotus. In the time of the Crusades it was discovered in Syria, and the Venetians learned something about it when the Crusaders returned to Europe. The Spaniards introduced the Sugar-cane to the Canary Islands in 1470. Then the Dutch took it to Brazil, and when they were expelled from that country by the Portuguese they transferred their canes to the West Indian Islands. Our English islands, Barbados (1643) and Jamaica (1664), soon found the cultivation a very profitable undertaking.130
The variations in price of sugar became in process of time of a very serious nature. In the year 1329 it is said that in Scotland a pound of sugar was worth one ounce of standard silver. But from 1780 to 1800 the price fell to 9d. The East Indian sugar began to compete with that from the West Indies about this time, but this was very soon crushed out by imposing a duty of £37 per cwt.
The West Indies were then very flourishing, but even before this the fatal word beet-sugar had already been heard. It was nothing at first but an interesting experiment by Professor Marcgraf in a German laboratory, who had extracted a little cane-sugar from beetroot in 1747. But in 1801 the beet was already in cultivation. Napoleon saw England's monopoly of the cane and judiciously encouraged the beet. The result of his far-seeing policy only became manifest a few years ago, for then the West Indian Islands, which we conquered and guarded against Napoleon at such fearful expense of blood and treasure, were almost worthless; Continental beet-sugar had ruined our colonial planters and our home refineries. It is in fact a most curious and interesting example of how a little judicious encouragement by a wise and far-seeing Government may destroy the profits of victory in a long, glorious, but yet ruinous war.
CHAPTER XXII
PLANTS AND ANTS
Meaning of Plant Life – Captive and domesticated germs – Solomon's observations denied by Buffon but confirmed by recent writers – Ants as keepers and germinators of corn – Ant fields – Ants growing mushrooms – Leaf-cutting ants – Plants which are guarded by insects – The African bush – Ants boarded by Acacias and by Imbauba trees – Ants kept in China and Italy – Cockchafer v. ant – Scale insects – A fungus which catches worms.
THE world of plants supports all animal life, from the mite to the elephant. There are most intricate relations between one form of life and another. Thus a Rose tree attacked by an aphis or green-fly may be succoured by the slim ichneumon, or other thin-waisted fly, which lays its egg in that of the aphis. Another insect, say a spider, catches the ichneumon. A starling may eat the spider, and be itself eaten by an owl.
So that ichneumon and starling are friends to the Rose, whilst the other insect, the spider, and the owl are enemies. Yet both the starling and the spider are probably, almost certainly on the whole, friends of the Rose, although they are unfriendly in this special case.
With all other similar series or changes the final term is either a bird or animal of prey or mankind.
Until we introduce the idea of man as the culminating point of the series, the whole of it seems to be without any special meaning or advantage.
But when we think of how man utilizes the work of plants and animals, then the whole scheme becomes intelligible and complete; it is like a well-rounded story with a worthy and adequate end.
Moreover, what man has done so far is only an instalment of what he will probably succeed in doing. All who have brought up caterpillars or bees know that their greatest difficulty arises from certain minute insects or fungus enemies. We already know enough about these latter to fight them with some chance of success, but there are hundreds of other spores and germs floating in the atmosphere, and coming to rest on animals, on clothing, or on the leaves or petals of plants. These germs are now just as wild as, and infinitely more dangerous than the furious aurochs, the disdainful wild asses, or the ferocious wolves that our forefathers succeeded in domesticating.
Those bacteria, or germs, for instance, which are only one-thousandth of a millimetre long, are only visible by the help of a microscope. A row of three hundred thousand of them would be required to make an inch in length! Yet one of these germs can be mature and divide into two new germs in twenty minutes. In forty minutes there would be four, in an hour eight, and so on. The number after twenty-four hours is almost incredible.
These little germs stick to our clothes, fingers, lips, money, newspapers, and anything that is often handled. They hover in the air we breathe, permeate the food we eat, and inhabit water, and especially milk, in enormous numbers. Some of them are deadly. One might easily decimate a whole population, as indeed happened in the South Sea Islands when smallpox was introduced. Others are harmless and even necessary.
But to-day if you go into a bacteriological laboratory you will find hundreds and thousands of little glass tubes all neatly labelled and stoppered with cotton wool. If you read those labels you will see that the bacteria of all sorts of horrible and loathsome diseases have been captured and imprisoned. There is the deadly anthrax bacillus peacefully discolouring gelatine; in another, possibly the germs of hydrophobia may be undergoing a process of taming or treatment.
Each of these colonies of germs is under perfect control, and in many of them their natural wickedness has been so much alleviated that they are now useful aids to the doctor, who gives his patient a mild dose of the disease in order to accustom his system to resist accidental infection by the original type.
Yet what has been done already is only an earnest of what will no doubt be accomplished. Every farmer and ploughboy will in time sow his own bacteria; every dairymaid will make all sorts of cheese, from Camembert, Rochfort, to Gorgonzola, by sowing the right kind of germ upon it.
Man will no doubt cultivate the whole earth in the way that he now cultivates Europe and Great Britain, and will obtain mastery not only over his domesticated plants and animals, but over fungi, bacteria, and insects also.
Even if man had never risen above the state of the Banderlog of Mr. Kipling, there are other animals which cultivate and even combine together for warfare and conquest. In some respects they are better disciplined even than man himself, and they can defy all sorts of mankind except civilized man.
Possibly if man had not arisen on the scene, these insects might have developed some sort of civilization like that imagined by Mr. Wells in his story of the moon. We are only concerned with the relations of these ants to plants. Those who are interested in their conquests and civilization must consult the excellent account by Mr. Selous in his Romance of the Insect World.
The most interesting points about them are as follows. They gather a harvest and store it up for the winter. This habit of the ant was well known to the ancients, and is mentioned by Solomon. At the time of the French Encyclopædists, when the fashion of the times was all for destruction and disbelief, the fact that ants do so was ridiculed and flatly contradicted, and especially by the great naturalist Buffon. They pointed out that ants hibernated during the cold weather, and therefore required no food for the winter, so that Solomon's story was absolutely ridiculous.
For nearly a hundred years people forgot that Palestine and those other countries where the habits of ants had been reverently observed possessed a climate much too warm and mild to make the ants hibernate.
After careful study it has been discovered that the ants thoroughly understand the first stages of brewing!
The corn which they gather is not eaten by them in its hard winter condition. When taken into the winter nest of the ants this corn would very soon germinate and grow into a plant, but the ants manage to prevent this by some method which is not yet understood. If such a nest is left alone by the ants, the corn immediately begins to grow, but it is not allowed to do so till it is required for food. Should the store of corn get damp by heavy rain, or mould appear upon it, then the careful ants bring up their store into the sunlight and dry it there.
When it is required for food germination is permitted, but is soon stopped: the ants nibble off the growing rootlet of the seed. Then when the grain absorbs water and begins to change its starch into sugar, the ants suck in the sugar and reap the reward of all this labour and skill.
In the conduct of this germination of the grain they are, of course, far in advance of all the savage races of mankind.
There are certain South American species which go at least one step farther. They have their own fields – spaces three or four feet in diameter – which are entirely occupied by one single grass, the so-called Ant-rice (Aristida stricta). Dr. Lincecum states that the ants "work" these plantations very carefully, removing every weed or other plant that comes up, and sowing every year the new seed at the proper season.131
These facts are sufficiently strange and startling, but there are even, apparently, species still more intelligent, who not only sow and reap, but actually prepare a soil and reap a crop of mushrooms, or at least, if not of mushrooms, of fungi. These wonderful little insects gather leaves and cut them into fragments of an appropriate size; they are then collected together so as to form a bed, and the fungus is introduced to this. The fungus is kept at a certain stage of growth by very careful treatment; the fruit-bearing ends are nibbled off, so that the young shoots come up indefinitely. The ants feed upon these fungus shoots, and get a crop indefinitely prolonged.
This is, of course, a system of agriculture far beyond that employed by any tribe of savages. Only man in a relatively advanced stage of agriculture grows mushrooms for himself. These facts, startling as they may seem, are apparently quite well authenticated and have not been seriously questioned.
There are a great number of leaf-cutting ants who are, indeed, amongst the most dangerous of the many insect pests in South America and elsewhere. Wallace (Revue Scientifique, 179, p. 29), in speaking of the Saauba or leaf-cutters, describes how he placed a large heavy branch across the route of one of their columns.
The long line of laden ants was checked, and the greatest confusion set in at the head of the column. Each ant, for several feet down the column, then laid down its leaf, and all set to work to tunnel under the obstacle. This was managed in about half an hour's time, and the column then proceeded on its way.
Amongst other interesting and curious facts connected with these extraordinary insects is that some kinds are actually kept up by certain plants as a sort of standing army or police.
There are no less than 3030 species of plant which keep these standing armies of ferocious ants, or if they do not keep them, at any rate lay themselves out to attract them. The kinds which are attracted live upon sugar, and are strong, active, and extremely good fighters. When travelling through the bush in Africa, it is not unusual in some places to touch inadvertently one of these protected trees. In a moment one's hand and arm are covered by ants whose heads are dug deep down into the skin, biting with all their strength.
It is of course impossible to describe all the plants which protect themselves against injurious insects and even large animals in this way, but two of them must be mentioned.
There are certain Acacias which are particularly interesting. Like most of this order, they have large hollow spines instead of stipules at the base of the leaf. It is inside these spines that the troops of the police-insects live. These Acacias (Oxhorn Acacia, as well as A. sphærocephala and A. spadicigera) also produce sugar, which is secreted by peculiar gland-like organs on the stalks of the leaves, and even albuminoids, for at the tips of the leaflets there are peculiar little bodies which contain albuminous matter.
