HE BOOKS IN NAT! Hi mil ft A A A /V A A A A TILLERS OF THE GROUND NEWBIGIN m 3\ ft (M ^\ A i presented to Sbe library of tbe of Toronto Hooks in JJataral Iftnotnleagt TILLEES OF THE GROUND MACMILLAN AND CO., LIMITED LONDON • BOMBAY • CALCUTTA MELBOURNE THE MACMILLAN COMPANY NEW YORK • BOSTON • CHICAGO ATLANTA • SAN FRANCISCO THE MACMILLAN CO. OF CANADA, LTD. TORONTO TILLERS OF THE GROUND A BY ^ th°Ugh the*V d° not the left have been capri- dry well. The figS which have most flavour when dried are the kind called Smyrna figs, and these must be caprified. Capri- fication means the carrying of pollen by tiny wasps from the wild figs to the cultivated ones. Next time we eat a dried fig, we should notice that at the top of the fig there is always the remains of the little hole through which the fig- wasp entered in order to fertilise the fig. fied, the wrinkled right- hand Figs have not. vin DATES IN NORTH AMERICA 89 In the next two chapters we shall consider how the Americans have had to toil in order to introduce dates and figs into North America. CHAPTER VIII INTRODUCING DATES INTO NORTH AMERICA THE Arabs grow dates so well and make so much use of them that the idea of introducing the date- palm into other countries with a suitable climate has naturally occurred to many people. So far as regards the Old World, however, it is remarkable that, ancient as is the cultivation of the date-palm, the area over which it is grown with success has always been limited. Thus, at different times, date- palms have been taken to China, a country of very skilful cultivators, but it has never been grown there on a large scale, and is not grown at all now. It was introduced by the Moors into Spain, but the date-palms of Spain are not to be compared with those of North Africa. Perhaps this is in part due to the fact that the date-palm is very particular as to climate, but it must also in part be due to the fact that it is difficult to grow. The people round the eastern and southern parts 90 TILLEES OF THE GEOUND CHAP. of the Mediterranean basin have grown dates for thousands of years, and they have acquired a kind of skill which it seems difficult for other peoples to acquire. We find, therefore, that, despite all their perseverance, knowledge, and cleverness, the people in the warmer parts of North America have taken a very long time to introduce the date successfully. It seems probable that they have succeeded now, but it is only after many attempts. The first attempt was made by the Spanish missionaries, who introduced many useful plants. They planted in California, during the eighteenth and the early part of the nineteenth century, date stones, brought either directly from Spain, or ob- tained from palms grown in Mexico from Spanish seed. The seeds so planted grew into fine trees, the descendants of which are still living and form great ornaments to the landscape of Southern California. This first planting had, however, several great drawbacks. In the first place, it was found that trees grown from seed consist in nearly equal numbers of pollen-bearers and fruit-bearers — that is, about half the trees bear no fruit. Secondly, Spanish dates are not very good ; we shall see directly that dates grown from seed are not often good. Therefore, though about half of the Spanish trees bore fruit, yet very few indeed of these had fruit which Americans think worth eating. vin DATES IN NOKTH AMEEICA 91 The next serious attempt was made from 1848 to 1880, when the Americans, as distinguished from people of Spanish descent, were beginning to develop the west. They also grew their date plants from seeds, but they got better seeds, brought from the region of the Persian Gulf. Some of the trees so reared bore good fruit, but relatively few of them did so, and again there was a great pre- dominance of pollen-bearing trees. The methods of cultivation also were not well understood; so that though these continued efforts produced some fruitful palms, yet they did not produce nearly enough to supply the demand in America for good dried dates. After some time it was recognised that the only way to start date-growing on a considerable scale was to get suckers from the good kinds of Arabian dates. Young date-palms, not the old ones, produce suckers round the bottom, after some- thing the same fashion as was described in the case of the banana. The Arabs never sow date seeds. They mark carefully in their gardens the best kinds of dates, and then the suckers from the young plants of these kinds are taken and used to start new plantations. It is, of course, only the fruit-bearing palms that are reproduced in this way, and thus the Arabs avoid getting a great number of useless plants, such as the Spanish Fathers got. That is the first advantage of their method. 92 TILLERS OF THE GROUND CHAP. The second one is a little more difficult to understand. Some of us have been shown how fruit trees are grown in this country, and we know that gardeners who want fine apples never think of planting apple pips, even from a very beautiful apple. They take a bud from a good apple tree, and graft it on another young tree, from which all the branches have been cut off. The bud grows on the stock, as it is called, and produces a tree exactly like its parent. If we ask the gardener why he does not just sow the seeds, he will tell us that the seeds do not " come true " ; that is, they do not grow into trees producing the same good fruit as the parent. It is much the same with the date. Date seeds do not always grow into plants which produce the same good fruit as the parent trees ; but a sucker taken from the base of the parent will produce exactly the same kind of fruit. This the Arabs long ago discovered. When it became clear to the Americans that they would never get very good date-palms until they brought over suckers from good kinds, they proceeded to try to do this. But this is not nearly so. easy as growing the plants from the seed. It is only necessary in that case to take a date out of one of the frilled boxes in which we get them, eat the date, plant the stone, keep it as warm as possible in its pot, and by and by the little date viii DATES IN NOETH AMEEICA 93 plant shoots up. To bring over a sucker means a great deal more trouble and expense. For fourteen years, from 1876 to 1890, different people went on trying to bring over suckers. They were brought over, a good many of them, but all sorts of accidents befell many. Some were washed out of the ground by the great floods of the Colorado river ; some died because the winters in the places where they were planted were too cold ; some were neglected by the people to whom they were sent, who thought the plants more trouble than they were worth ; some were carefully tended, and then turned out to be nearly useless, because the people from whom they were bought had not chosen to send the best kinds. But even with all these accidents a few plants survived and did well in certain places. There were enough of these to prove to intelligent people that the date-palm could be made to grow in the western parts of North America, and that all that was wanted was patience", perseverance, and skill. Therefore, in 1899, the Bureau of Plant Industry took up the matter seriously. An expert was despatched to North Africa to choose, buy, and ship offshoots of the best kinds of date-palms, and at the same time to learn all he could about methods of culti- vation as practised in the regions where the best dates are grown. It took about three years to 94 TILLEES OF THE GKOUND CHAP. carry out this commission; but by 1901 the date was fairly established in parts of Western North America, where it seems likely to do well. Thus it took more than a hundred years to establish the date thoroughly in the New World. Let us look at the work of the American expert FIG. 22. — Setting out Date Offshoots from North Africa in Arizona. in a little more detail, and see how he got the offshoots of the- good kinds, what he learnt by studying the Arabs' date gardens, and what kind of advice he was able to give the American cultivators. To get the best offshoots possible, he went to Biskra, the garden of dates, which lies in Algeria on an oasis close to the northern boundary of the Sahara desert, and just south of the Atlas Mountains. viii DATES IN NOETH AMEEICA 95 At the oasis of Biskra there are about 160,000 date-palms, planted, as the Arabs do plant them, without any order or arrangement. Eound the central oasis there are some smaller oases, so that altogether there are about 500,000 date-palms near Biskra. Each tree produces, on an average, from 100 to 200 pounds of fruit in the year, so that this is date culture on the large scale. Somebody of a mathematical turn of mind will perhaps tell us how many tons of dates are likely to be grown at Biskra every year ? More than this, though the blazing sun of the desert will not permit other trees or plants to grow without shade, yet it is possible to grow them under the shade of the date-palms, so that these have another use besides fruit-yielding. At Biskra, as Fig. 23 shows, figs are grown under the shade of the dates, and in some places it is usual to grow vegetables beneath the figs. There are thus three tiers of plants : — The great date-palms first, towering high up in the air ; then beneath them fig trees or even peach, apricot, and almond trees ; and beneath these fruit trees again, garden vegetables, protected from the deadly sun by the trees above. The expert was, however, not content with his visit to Biskra. He travelled ninety miles farther south into the great desert, down to some special plantations grown by French colonists. Here he 96 TILLERS OF THE GROUND CHAP. bought suckers and studied methods, and finally loaded a caravan of camels with the results of his FIG. 23. — Fig-trees growing beneath Date-Palms near Biskra. search, and set off northwards again. There were many difficulties in the way of getting his precious offshoots across the sea. In the long run, how- ever, all these were overcome, and the suckers were viii DATES IN NORTH AMERICA 97 carried vid New Orleans to Arizona. Here they were set out in an experimental garden, after having been carefully fumigated in case there should be any dangerous insect pests brought over with them. But the offshoots were not enough ; the question of how they should be grown is just as important, and the expert had therefore to learn all he could, and, with the help of others, to apply the knowledge he gained in this way to the special conditions of North America. We all know the Arab proverb which says that the date should have its head in the fire and its feet in the water, or, to put the matter more poetic- ally : " The date-palm, the queen of trees, must have her feet in running water, and her head in the burning sky." It was not just at once, how- ever, that the cultivators learnt that this means that the date is not a true desert plant like the Mexican cactuses. It is not an inhabitant of the Sahara, but of the oases of the Sahara. It will not ripen its fruit in a country where there is summer rain or where the air in summer is damp ; but it will not grow at all unless the roots have abundant water. Now this combination of requirements means generally that the date-palm must be artificially irrigated ; and it is this which makes it expensive H 98 TILLERS OF THE GEOUND CHAP. to grow. For this reason also the cultivator can only afford to grow the smallest number possible of pollen-bearing trees. Further, in the oases where it grows naturally, and where the air in summer is very dry and very hot, the soil often contains alkali and salt — to these the date-palm is remarkably resistant. If it can get water for its roots, it does not mind if this water is brackish. This is a very important point in connection with its growth in countries like Arizona. Next to the bringing of the requisite amount of water to the roots of the date, which is often a very laborious process, the most troublesome part of date-growing is fertilising the flowers. At this the Arabs are very skilful, but at best it is a tedious and laborious process. As we have already seen, each date-palm requires a large amount of water, and, in the country where date-palms grow, water is one of the most precious commodities there are. Therefore, while in the wild state there are as many pollen- bearing dates as fruit-bearing, the Arabs only allow one pollen palm for a hundred fruit palms. So much pollen is produced that there is then enough if the pollen is not wasted, as it is in a state of nature. A great difficulty, however, is to be sure that the pollen palms and the fruit palms will flower at the same time. It does not matter much VIII DATES IN NORTH AMERICA 99 if the pollen flowers open before the fruit flowers ; for the pollen wiH keep for a long time, but it is very serious if the fruit flowers are ready to be fertilised before the pollen flowers have opened. FIG. 24. — Pollen Flowers of Date-Palm. FIG. 25. — Fertilised Fruit Flowers of Date- Palm. Owing to their long experience, the Arabs have found means to make sure that the two kinds of palm flowers will open at the same time, but in America this is one of the difficulties which requires much care in overcoming. The Arab also, knowing how supremely im- 100 TILLEES OF THE GEOUND CHAP. portant the fertilisation is, always takes care to keep a little store of pollen in* case of accident. Pollen will keep in a dry climate for at least two years. How does the Arab fertilise his dates? Well, the pictures help to show us. He takes a little twig of pollen flowers, then he carefully opens the sheath of the fruit flowers, slips in his bunch of pollen flowers, ties it in position with a piece of palm- fibre, and then he knows that there is always sufficient movement in the air to make sure that the dust will be carried to each of the flowers in the fruit-bearing cluster. When the palm trees are young the task is easy, for the Arab can easily reach the flowers. When they grow older, however, the trees become very tall, and then it is difficult to reach the FIG. 26. — Arab climbing Date-Palm to fertilise Flowers, Biskra. viii DATES IN NORTH AMERICA 101 flower clusters. The Arab, who is lithe and supple, climbs up the tall stems with his hands and his bare feet, holding the bunch of pollen flowers and the fibre in his mouth. Quite often he has to ascend the same tree several times, as all the flower clusters do not appear at once, and each one must be fertilised separately. So clever is he, however, and so well have his eyes been trained, that he rarely misses a palm, hardly even a flower cluster. Each tree in full bearing is allowed to produce eight to twelve bunches of fruit ; that is, eight to twelve flower clusters must be fertilised. How much tree-climbing then must go on each year before the 500,000 palm trees of Biskra are fertilised each year ? Perhaps, when the Americans have grown dates for some time, they will learn how to do the pollinating more simply than the Arabs do it, but that will take some learning. With all these difficulties is there hope that dates can be grown profitably in North America ? Well, it seems that in parts of California and Arizona, especially, dates can be grown more profitably than any other plant, because in these places we have the hot dry summer which is necessary to ripen the fruit ; the water can be brought to the roots by irrigation, and this water and the soil often contain so much alkali that not many other plants will grow, whereas the date will 102 TILLERS OF THE GROUND CHAP. grow in such soil without difficulty. It is, how- ever, too difficult a tree to grow in a haphazard fashion, and, as we have shown, if success is now within sight, it is only because infinite care and trouble have been spent on learning the why and wherefore of the things that the Arabs do by rule of thumb, for the simple reason that their fathers did them before them. CHAPTER IX THE STORY OF THE SMYRNA FIG IF the introduction of the date-palm presents some difficulties, that of the fig presents many more. In the first place there is the puzzling uncertainty as- to whether caprification is really necessary or not ; and then if it is — and experience has proved that it is necessary with the Smyrna fig — the complica- tions are just beginning. In the case of the date- palm the chief difficulty is to grow the two kinds of palms, and to grow them in the right proportions. In the case of the fig the cultivator must grow (1) the fig proper, (2) the wild fig or capri-plant, (3) he must see that the caprifigs contain the little wasp. As we shall see, all these three presented ix STOEY OF THE SMYENA FIG 103 difficulties which took some time and patience in overcoming. Figs grow freely in Spain and in France, and, therefore, as in so many other cases, it was the Spaniards who first took them to America. In this case the Spaniards were assisted by the French, who took their own figs with them to the Southern States. Throughout the greater part of the Southern and Western States, then, fig trees are common and fruit freely. But the fruit is eaten green, either fresh from the tree, or stewed, or preserved. Sometimes it is tinned, as peaches and apricots are tinned ; only rarely are attempts made to dry it. One reason for this is that, in the South, figs ripen at the time of the summer rains, when drying would be difficult. The result is that, until recently, the fact that figs grew all over the warmer parts of the States did not prevent an enormous import of dried figs from Turkey ; this import at one time being thirteen and a half million pounds weight per annum. These imported figs are of the kind called Smyrna figs, the kind that comes to this country in the familiar little wooden boxes, and which we eat in the winter months. What the Americans wanted to do, then, was to supply this demand for dried figs, and not simply to be content to grow green figs for home use. For some time an attempt 104 TILLEES OF THE GROUND CHAP. was made to dry the figs grown in California, where there are riot summer showers to spoil the process, as in the Southern States. But the public, accustomed to the well-flavoured Smyrna figs, would not eat the tasteless home-grown varieties. What was to be done ? It seemed clear that the answer was — get some Smyrna fig plants and try them. This was done, first apparently about 1880. It was done by a Californian who had a newspaper connection, and therefore, in the American fashion, he took care that everybody should know that henceforth Smyrna figs were to be grown in America. Thanks to his efforts every- body did know, but unfortunately when the cuttings that he brought over came into bearing, it was found that they refused to ripen their fruit ; the fruit dropped off when each was no bigger than a marble. It was clear that something was wrong ; but still the first step had been taken — the Smyrna fig plant had been brought over. Some eight years later another Californian imported fresh Smyrna fig trees. It was thought that perhaps the first importations had not been good kinds, that the fig-growers in Turkey had sent rubbish because they were afraid of losing their market. This time, therefore, a trained gardener, Mr. George C. Eoeding of Fresno, California, ix STORY OF THE SMYRNA FIG 105 went to Smyrna, and not only bought plants but also studied methods, and as a result brought back caprifig cuttings as well as the edible fig plants. Two years later, that is in 1890, both kinds of figs came into bearing, and the Smyrna figs were artificially fertilised by taking some of the pollen out of the caprifigs, and, with the help of a quill, putting it inside the edible figs. As a result four ripe figs were obtained. The year after — we can see what time and patience must go to this kind of work — a glass tube drawn out to a fine point was used, and the pollen blown into the edible figs. This time one hundred and fifty edible figs were produced. Thus, after eleven years of experiments, it was shown that the Smyrna fig would grow in California, and that before it would ripen it must receive pollen from a caprifig. This was the second step — the introduction of the caprifig. Perhaps some one may say, Why not stop here ? If the date-palm is always pollinated by hand, why not the fig ? But let us think for a moment. In the case of the date each duster is fertilised by hand, but each cluster may contain ten or twenty pounds of dates; it is a very different matter blowing pollen into each single fig with a little glass tube — that could never pay. If the fig-wasp could be introduced into America, it would carry the pollen from the caprifigs to the edible figs, and 106 TILLEES OF THE GROUND CHAP. thus save all the trouble. The difficulty was to get the wasp. It lives in the caprifigs, but there were, of course, no caprifigs on the cuttings of capri- plants brought over from Europe, so how was the wasp to be got ? How was the ' third step to be taken ? Well, a great many ways were tried ; it would take too long to tell about them all, but' it became FIG. 27. — Capriticated Figs, whole and cut in half to show Flowers within. clear that success was impossible until the life- history of the wasp was understood thoroughly. Some work had been done already on this question in Europe, some still remained to be done, and further, the peo »le who were actually working at the subject in California had not only to learn what had been done in Europe, but had also to find out how the conditions in California differed from those in Europe. We may state very shortly what they learned, and show how it helped them to final success. ix STORY OF THE SMYRNA FIG 107 But before going on to this, something else may be said. There are certainly people who will say, What greedy people the Americans must be to take so much trouble over figs and dates ! They may be very important to the Arabs in the Desert of Sahara, but what do they matter in America where there are plenty of other fruits ? The only answer we can make to that objection is, that if there had not always been on the eartli people who were determined not to be beaten, even in trifles, who would go through with a thing because they had begun it, we should all have starved long ago, or have been reduced like the poor Australians to scratching a few miserable roots out of the soil. Civilised man has prospered, has become civilised, just because he has been determined to go through with things, to find out why they were failures, even if he could not always make them a success. Now let us go back to the fig-wasp. What was found out was this — there are three crops of wild figs : a spring crop, a summer crop, and an autumn crop, which hangs on the trees till spring. The little fig-wasp passes the winter in the autumn caprifigs ; but when spring comes it has exhausted the food in these, becomes restless, and, leaving the withering fig, emerges into the air. By this time the plant is beginning to produce its spring crop of caprifigs. These the wasps enter, 108 TILLEES OF THE GEOUND CHAP. and, within them, they lay their eggs and die. The eggs hatch into new wasps, which feed upon the caprifig until they have exhausted the food it contains. The new wasps must then in their turn leave the caprifig and go forth to seek a home in which they may lay their eggs. But the spring caprifigs are full of pollen, therefore, when the wasps emerge, they are covered with pollen. If the fig-grower takes these caprifigs before the wasps have left them, and hangs them over a tree containing edible figs, then the wasps, as they emerge, find their way into the edible figs. They cannot lay their eggs there, for the flower is not arranged to suit them, but they blunder about looking for a suitable place, and in this way they fertilise the little flowers inside the fig. That is, they do what the fig-grower wants them to do. Finding no convenient place for their eggs in the edible figs, they come out of them again and seek the caprifig trees, where they lay their eggs in the summer caprifigs. In the autumn the wasps leave these for the autumn figs, and in these autumn figs they pass the winter, to begin the whole process over again in the spring. From the wasp's point of view, therefore, the visit to the edible fig is merely a waste of time, because the edible fig has lost, in cultivation, everything that makes it useful to the wasp. But, as the ix STOKY OF THE SMYKNA FIG 109 resemblance between the two is close, the wasp is easily deceived into paying a visit to the edible fig if the grower is careful to bring the caprifigs close to the edible figs. If he does that, then the wasps do their duty, enter the edible figs, fertilise them, and so make them fat, juicy, and well- flavoured. But the fig-grower must not stop here. He not only wants to have wasps to fertilise his figs this year, he must be sure that the stock of wasps is kept up so that he may find fresh wasps next year — that is, he must have growing in his orchard capri-trees bearing summer caprifigs ready to receive the wasps when they have fertilised his edible figs. If he has not such trees, then the wasps will die, and there will be none for next year. Thus he has to cultivate fig-wasps (remember they are quite different from the common wasp, and very much smaller), as well as figs and caprifigs. It is rather a complicated matter ! The first difficulty was to get the wasps alive to the States, and this was found very difficult. Not until it was learnt that only the resting-wasps in the autumn caprifigs would stand the journey was this possible, and it took a long time to learn this. After much hard work and many attempts, in the spring of 1889 boxes of winter caprifigs were 110 TILLERS OF THE GROUND CHAP. sent from Algeria to California, and arrived full of resting-wasps. These figs, with the contained wasps, were placed beneath a caprifig tree in California, the tree being carefully covered over so as to prevent the escape of any wasps. Everything was done with the greatest care, but the people in the orchard had very little faith in the result. They thought the wasps were probably dead, and they had tried so long that they seem to have become a little hopeless. However, with or without faith, they took all the trouble they could. The care was justified, for by the autumn it was found that this caprifig tree was loaded with capri- figs, many of which were full of wasps ready for the winter. In spite of the tent over the tree also, some of the wasps had escaped, some had fertilised edible figs in the orchard, and some had found a winter home on neighbouring caprifig trees. Would the precious wasps live through the winter ? That was the question. Everybody was determined that all man could do should be done to help them to do it. Besides the original caprifig tree, two neigh- bouring trees were found to have so many wasps in their figs as to be worth protecting. Round these three trees an elaborate canvas house was built, so arranged that in fine weather the trees could be simply covered, but if frost was probable they ix STOKY OF THE SMYBNA FIG 111 could be carefully protected from the cold. On these three trees about a thousand caprifigs con- taining resting-wasps were counted. This done, there was nothing more to do except wait for the .spring. When the spring came it was decided that the subject was so important that a special expert from the Department of Agriculture should be sent to watch events. This expert spent almost his whole day in the orchard, watching the insects, and trying to find out all that was happening. About the •end of March the wasps finished their winter sleep and began to come forth. By this time the capri- fig trees were beginning to produce their spring crop, and into these the emerging wasps passed to lay their eggs. This went on for about five weeks, and the result was the swelling up of a number of the spring figs, showing that the wasps had entered them, laid their eggs there, and the young wasps hatched from the eggs were now feeding upon the interior. By the early part of June the wasps had ex- hausted all they could find in the spring figs, and began to emerge in search of new figs in which they in their turn might lay their eggs. This was the critical moment, for it was these emerging wasps •which were relied upon to fertilise the edible figs. All hands were set to work, and the party was 112 TILLEES OF THE GKOUND CHAP. divided into three groups. One party gathered the caprifigs with their wasps inside, and carried them to headquarters. Here they were strung in FIG. 28. — Carrying the strung Caprifigs to the Fig Orchard. bunches on a piece of fibre, the strings being then hung over long poles so that they could be easily carried. The second party carried these strings of caprifigs back to the orchard, and the third had the more delicate work of suspending the strung figs ix STOEY OF THE SMYKNA FIG 113 over the branches of the trees which bore edible figs. The work was not all very simple, for, as it was new to every one, there was no experience to act as guide. In the first place the caprifigs had to be sorted carefully, to make sure that they did contain wasps. Then the stringing was not easy. Strong needles were used, but it was found that a milky juice came out of the caprifigs, which soon clogged the needle and soiled the fingers. This juice also affected the fingers of the workmen, so that they became sore and burning, and this was made worse by the constant washing that was necessary. But, difficult or easy, the work was done ; and up and down the orchard of edible figs could be seen the strung caprifigs hanging from the trees. From the caprifigs the wasps soon emerged, and, seeking the edible figs among which they found themselves, they fertilised these, before coming out again to seek for caprifigs. The experiment proved a huge success. From one cause and another the thousand winter caprifigs with which it began were reduced by the spring to about four hundred and twenty, but from these enough wasps emerged to produce a great many wasp-containing spring figs, and the result of the fertilisation was about twelve to fifteen tons of good I 114 TILLERS OF THE GEOUND CHAP. Smyrna figs, in spite of many losses due to in- experience and various minor difficulties. Here, then, was the third step, the introduction of the fig-wasp, successfully accomplished. After ripening, the figs were dried in the approved Smyrna fashion, packed in boxes, and proved, according to those who tasted them (but perhaps they were partial !), to be better than the best Smyrna figs. What is certain is that the experiment succeeded, so that after nineteen years of effort the Smyrna fig was grown finally in California. A little difficulty was experienced in making sure that the wasps would find suitable caprifigs in which to lay their eggs after they had emerged from the edible figs, but this was got over, and all that remained to be done was comparatively simple work — the great steps had been taken. Three years later, the orchard where these first experiments were carried out produced sixty-five tons of good fruit, and the work is going on steadily now. It is true that the industry of growing and drying the figs is still in its infancy, for the California orchards cannot yet supply anything like the demand that there is in the States for dried figs, but there is every reason to believe that it will go on and prosper. Further, while in Turkey the methods of drying and preparing the figs are not ix STOEY OF THE SMYENA FIG 115 always conducted with as much care as they might be, in California great care is being taken as regards these points, and this will, no doubt, make a difference in the taste and value of the figs. The Americans have, at least, reason to be proud of their success so far, and this success has been due to the fact that, instead of being content to wrap ignorance in fine phrases like Pliny, men have spent their lives in toilsome and not directly productive work. CHAPTEE X FOOD AND FOOD-PLANTS WE have spoken of the origin of food-plants and of the way in which they have been carried by man over the globe, but we have not as yet said anything of the general characters of food-plants. It is, however, necessary to do this before we can discuss the way in which man has succeeded in improving his food - plants, in making them better, more fruitful, and better fitted for the different countries to which he has carried them. To begin with, we should notice that the important cultivated plants fall into three groups : — 116 TILLERS OF THE GROUND CHAP. 1. Those cultivated for their seeds. 2. Those cultivated for their roots or under- ground stems ; and 3. Those cultivated for their fruits. There are, of course, also plants like cabbages and lettuces which are cultivated for their leaves ; plants like cloves which are cultivated for their flower buds ; those like cinnamon cultivated for their bark ; those like sugar-cane cultivated for their sap ; and so on. " Speaking generally, how- ever, it is the seeds, the underground parts, and the fruits which are important to man for food. Of these by far the most important are the seeds, and this for several reasons. In the first place, seeds contain, bulk for bulk, less water and more food material than other parts of plants. Another reason, which must have weighed much with primitive man when he began to cultivate the ground, is that the plants which produce the greatest bulk of seeds are annuals, that is, they grow faster than other plants, so that the cultivator does not have to wait so long for his crop as if he were growing fruit trees, for instance. But before saying more about the different kinds of cultivated plants, we must say a few words about food, so that there shall be no confusion in our minds. In order that we may keep in health we must have three different things in our food. The x FOOD AND FOOD-PLANTS 117 chemist gives these three special names, and there are many conveniences in learning these three names, though two of them are never used in daily life. The first, and in some ways the most important, is proteid. Many people would use instead of this name the everyday word meat ; but this is not exact, for though meat consists of proteid yet we have to remember that bread, for instance, and other vegetable foods also contain proteid. No animal can live without proteid, but we know that the cow does not eat meat — she gets her proteid in the grass which she eats. But as, bulk for bulk, there is always less proteid in plants than in animal matter, the cow must eat far more proportionately than the cat, which eats meat. In the same way with man, the people who eat meat do riot need to take so much bulk of food as the people who live on vegetable food only. The second substance which we need in our food is what is called carbohydrate, which is simply a convenient word to include both starch and sugar. We need far more starch or sugar than proteid, and the bulk of our food is, or should be, carbohydrate. Bread, for instance, is largely made of starch. Finally, we need an amount of fat, which varies with the climate and the season, and can be got either from plants or animals. 118 TILLEKS OF THE GROUND CHAP. We need proteid because our bodies are made largely of proteid, and there must always be some proteid added to make up for waste and to allow for growth. We need starch and sugar because we are always moving about and working, and it is starch and sugar which give us energy to move. We need fat to keep us warm, and therefore we need less in summer than in winter, and people in warm countries need less than people in cold. A missionary who lived with his family in the Far North of America, where the cold is terrible, tells us that if you offered his children a candle- end with one hand and a lump of sugar with the other, they would always seize the candle first and eat it with delight. In the same way when Nansen crossed Greenland, he tells us what a fearful craving all his party had for fat of any kind. They each got an allowance of butter, which had to last the week, but most of them could not make this allowance last the week ; the temptation to eat it in great lumps was so strong that they could not resist it. Both these little stories show us how important fat is in a cold climate. On the other hand, in a warm climate like Italy the people practically do not eat butter at all, and take very little animal fat. They take what fat they need in the form of olive oil. Northern people could not do this x FOOD AND FOOD-PLANTS 119 because olive oil is not very easy to digest, and it would be impossible to take all the fat that is necessary for them in that form. To sum up then, wherever man lives he must Fia. 29.— An Olive Grove. have in his food proteid, carbohydrates, that is starch and sugar, and fat. The farther north he lives, however, the more fat he must have, while in warm climates very little fat is necessary. It seems also to be true that in the colder climates he 120 TILLEES OF THE GEOUND CHAP. requires more proteid than in the warm ones. For both these reasons vegetable food is more important to people in warm climates and animal food to people in cold ones, for they must have much digestible animal fat and much proteid. For instance, the Eskimo in the Far North take practically no vegetable food, while many of the peoples in the tropics take practically * no animal food, and between the two we have all gradations. Now let us go back to the kinds of plant food. We find that the seeds which man uses as food contain more proteid and more fat than any other parts of plants. The roots which he uses usually contain a certain amount of proteid, but very little fat ; their chief contents are starch or sugar. Fruits contain chiefly sugar or more rarely starch ; they have very little proteid, and not usually any fat. The reason of all this is easily seen. Seeds, as we know, contain the young plant. Just as the cow's milk contains everything that the calf wants, so the seed contains everything that the little plant wants till it is able to feed itself, except one thing. The calf requires at first absolutely nothing but milk, but the little plant cannot begin to grow until it is supplied with water from without, for the seed contains very little water. It is, therefore, a very compact mass of food-stuff. x FOOD AND FOOD-PLANTS 121 Consider next a root, like a carrot or a turnip, or an underground stem, like a potato. All these contain a store for the plant which is to re-start growing in the spring, therefore all contain proteid and starch, and perhaps a little fat. But while the seed must be small because it has to be carried away in some fashion to a distance from the parent plant, the root or stem, which in nature remains in the ground, need not be small. We therefore find that such roots and stems contain a good deal of water — the water which is absent in the seed. Suppose we were on a sinking ship, and were only allowed to make up a small bundle to take with us into the lifeboat, we should take only the most precious things, should we not ? Well, the annual plant is the sinking ship, and, as it can only give its offspring, the seeds, a small bundle, it is necessary that that bundle should only contain valuable things. Therefore, the seed contains a relatively large amount of proteid, which is the most precious thing ; it often contains fat, which is the next most valuable thing ; and the rest is filled up with the cheaper carbohydrates. In roots, where size does not matter so much, there are fewer bank- notes, that is, less proteid ; but there is a lot of spending money — shillings and sixpences and coppers, heavy to carry but useful to have, The spending money consists of starch or sugar, 122 TILLEKS OF THE GKOUND CHAP. which enables the plant to start growing very quickly in the spring. Finally, let us look at the fruits. They are very different from either seeds or roots. The substances in the fruits are of no direct use to the seeds, they are given away as a bribe to persuade some animal to carry away the precious seeds to a distance from the parent plant. Look' at a bird pecking at a wild -rose hip. He pecks the nice red cover, which is sweet and pleasant. But as he pecks he breaks through the red cover, and the hairy seeds come out. They stick to his beak in an uncomfortable way, so he wipes his bill on the ground to get rid of them. In that way he plants the seeds, which would otherwise fall close to the mother rose and be choked by all growing together. The rose, therefore, practically says to the bird : " You carry my seeds away for me and I will give you some nice sugary pulp for your trouble." It is like giving a boy a pennyworth of sweets to carry a message. But the rose has to be economical ; it must provide for its own children, the seeds, first. It is as if the rose said to itself: " I cannot give the bird who carries my message for me proteid, because my own children need all I can give them. I cannot give him fat, because that is dear too, but I have plenty of starch and sugar, he can have that, and I will give him as x FOOD AND FOOD-PLANTS 123 well some flavouring, and colour the fruit-case a pretty colour, and then he will be quite content." That is what is actually done by the rose, and is what happens in the making of most fruits. That is, they contain water, sugar, or sometimes starch, flavouring matter, but not much else. Generally, though they are a good addition to our food, they would not form a diet by themselves. But many plants, which in the wild state have very poor fruits, if they are cultivated and well fed, can be made to give a great deal more to the fruit, and thus render it more useful for man's food. Now what does all this mean from man's point of view ? Does it not mean first that the most important part of his plant food must be seeds, for it is only in them that he is likely to find much of the necessary proteid ? Perhaps it may be said that the banana-eating Baganda, whom we read about in the first chapter, form an exception to this, but remember that the bananas which they eat have no seeds ; the proteids which in the wild bananas went into the seeds, in the cultivated one go into the fruit pulp. Except where people are purely meat- eaters it is generally true that some kind of seeds, or a flour made from seeds, forms the chief part of their diet. For example, wheat, in the form of bread, forms the basis of the diet of many peoples, and rice of a great number more. Perhaps 124 TILLEES OF THE GEOUND CHAP. it may be said that we eat so many different kinds of things that wheat only plays a subordinate part in our diet. But if we think for a moment we shall see that bread forms part of all our meals, and though bread and water is not a diet that we should care to live on for long, yet we know that it is possible to live on it for a time. The geologist, Hugh Miller, who from being a poor quarryman rose to be a great man of science, tells us, in the story of his life, that when he was a journeyman he and his companions lived entirely on oatmeal, in the form of porridge and oatcake. So long as they could get milk to take with their porridge they were quite content; it was only when the milk -supply failed, and they had absolutely nothing but the oatmeal, that they felt themselves a little hardly used. The fact that they did live upon it, however, shows that the seeds of the oat- plant, without anything in addition, can supply man with the three necessary food substances, though they are poor in fat. But though seeds furnish probably the most important part of man's vegetable food, yet some kinds of roots and underground stems are also very important. We saw before that yams, which are the underground stems of plants distantly related to our leeks, form the chief food-supply of some kinds of African negroes. Similarly, potatoes are FOOD AND FOOD-PLANTS 125 very important as food in Ireland, but there they are of course helped out by other kinds of food. Though some kinds of roots are very nutritious yet, as a general rule, they are poor in proteid, and so must be used with other foods, and especially with some kind of seeds, such as cereals (wheat, oats, etc.) or pulse (peas, beans, etc.). As to fruits, we find that, as a general rule, they are much more important in warm than in cold countries. We must not suppose that this is because fruits only grow and ripen in hot countries. On the contrary, what gardeners call the " small fruits " will only thrive in cool countries. Nowhere do strawberries grow as they do in such countries as England where the summers are not very hot. In the high Alps, and in Norway and Sweden also, there is in autumn a wealth of berries — such as bilberries, cowberries, cranberries, and so on — which is quite peculiar to these parts, and is not even suggested in hot countries. But while fruits almost satisfy the appetite of the inhabitants of hot countries, in cold countries they only form a dessert, an extra. There is so little in them but sugar and flavouring matter that they hardly count as real food, except in those countries where very little food is required. In addition to giving man food in the form of seeds, roots, or fruits, the vegetable world gives 126 TILLEES OF THE GKOUND him also a great number of flavouring substances, which are of great importance, especially when he lives largely on vegetable food ; for this is often tasteless by itself. We have seen already that the FIG. 30.— Picking Tea in Ceylon. early Mediterranean civilisation depended chiefly upon wheat, upon the olive which gave fat, i.e. olive oil, or upon sesame which also gave oil, upon the wine which gave a pleasant drink, and upon fruits, such as figs or dates according to the country. But flavouring plants, such as garlic, were added to these very early ; and later the commerce x FOOD AND FOOD-PLANTS 127 between the Far East and the West largely began through the desire of the West to have the spices and the pepper of the East. We must not, there- fore, forget these flavouring plants in speaking of man's vegetable food, though they rather help to render his food digestible and palatable, than act as food themselves. Nor should we forget such plants as tea, coffee, or cocoa, which yield stimulating drinks, used by all civilised people. CHAPTEK XI THE CHIEF KINDS OF FOOD-PLANTS WE must consider next the kinds of plants which give to man the most valuable seeds, roots, and fruits. As regards seeds, two families are by far the most important, these families being the Grass family and the Pea family. It is not too much to say that man could not have spread over the globe as he has done, if it were not for the existence of these two families. Here and there, it is true, scattered over the different quarters of the globe, we may find small groups of men who owe little to these plants ; but it is true for the vast majority, 128 TILLEES OF THE GBOUND CHAP. both for themselves and for their cattle, that it is the grasses and peas and beans that feed humanity. The leaves of many kinds of grasses, and of such members of the Pea family as clover and lucerne, form forage for the domestic animals, while the seeds of other kinds feed man himself. Both families contain a considerable number of annuals, that is of fast-growing plants Which throw all their energy into seed -making, and die of exhaustion as soon as their seeds are full-formed. In consequence, the seeds are big and plump and full of food material. Further, they are for the most part without the poisonous sub- stances found in many seeds, which render them unfit for food ; they only require cooking to form an important part of man's diet. Let us stop just for a moment at this word " cooking," to ask ourselves why seeds cannot gener- ally be eaten without cooking, while we often eat fruits raw. The explanation is found easily if we go back to the question of the contents of fruits and seeds. We saw that fruits generally contain sugar, while seeds generally contain much starch. Now starch is difficult to digest when eaten raw ; it is much easier to digest when it has been altered by the heat used in cooking. We do not generally, it is true, cook nuts, which are seeds full of starch ; but then we eat very few nuts at a time. If we xi CHIEF KINDS OF FOOD-PLANTS 129 tried to eat many, we should be obliged to cook them. When man learned to live largely on seeds he had also to learn to cook his food, and that was a great step in advance. It seems to us a horrible idea that people should eat uncooked meat : but yet, really, there is less need to cook meat than to cook vegetables. Cooked meat may be less, not more, digestible than un- cooked, but there are many vegetables that are quite indigestible until they are cooked. Learning to cook must have taught man many things. It meant the beginning of pottery ; it meant the development of skill and patience ; as well as of many other useful qualities. More than that, the degree of ease with which the different kinds of vegetable food can be cooked must have influenced man greatly, in the early days, in deciding what kinds of plants he would cultivate. The seeds, which we call pulse, such as the different kinds of peas and beans and lentils, are generally more nutritious than the cereals like wheat and rice and oats. We should imagine then that pulse would be cultivated more generally than the cereals ; but we know that it is the contrary which is true. There were some peoples, the ancient Mexicans, for instance, who lived very largely on pulse, but these races were never so numerous as the peoples who lived chiefly on cereals, such as wheat and rice. K 130 TILLERS OF THE GROUND CHAP. The reason is that the cereals are cooked more easily and are more digestible, and, therefore, better suited to be eaten in quantity. In an earlier chapter we saw that there were three great centres in the world where agriculture began and cultivated plants were produced. It is interesting to consider what were the chief seed- producing plants in these three places. In the great agricultural area at the eastern end of the Mediterranean, the great seed-producing crops were first barley and later wheat. In the warm parts of America, the great food -plants were beans and Indian corn. In the Far East, though wheat was introduced into China very early, the most important plants were rice and millet. Now of all these food-plants wheat seems to be the best. It contains more nitrogen than rice or maize ; it is more digestible than beans. It has one great advantage over the other cereals in that it contains a large amount of a sticky substance, which enables it to be made into light bread easily. We all know that oatmeal, for instance, cannot be made into a proper dough Mke wheat flour. It is this power of forming a dough which makes wheat flour*so digestible. Now it is rather interesting to notice that so far in the battle of civilisation the wheat -eaters •re won. Wheat was first grown in the Mediter- xi CHIEF KINDS OF FOOD-PLANTS 131 ranean area, but it soon spread. All the nations which got their civilisation in whole or in part FIG. 31. — North American Indian Woman pounding Indian Corn. After pounding, the meal is sifted through the baskets, the finer parts being made into bread and the coarser into hominy. from the Mediterranean region, learnt also to grow and to eat wheaten bread. The process was a slow one. The story about Hugh Miller reminds us 132 TILLEES OF THE GKOUND CHAP. that it is only comparatively recently that wheaten bread became the usual food of the Scottish people, and in many parts of Germany a great deal of rye bread is eaten still. At the same time it is generally true that the peoples of Europe are wheat- eaters ; they eat wheaten bread when they can. When the Spaniards conquered America, the conquest meant practically the crushing of a bean- and maize -eating people by a wheat -eating one. All the countless fields of wheat, which are now to be seen in America, show how completely the Europeans took their love of wheat with them to America. Hitherto also it has been true that the wheat- eating peoples have, on the whole, been more energetic and done a bigger share of the world's work than the rice-eating people of the East, whose diet is poorer and less digestible. It is one of the interesting questions which the future must decide, whether the Japanese and the Chinese will continue to be largely rice-eaters, or whether they also will learn our habit of eating large quantities of wheaten bread, and if they do learn this, whether it will make a difference in the kind of work they do. But we must go back to the important seed- producing plants. Probably wheat is the most important of all, but there are a great number of others. In the Old World we have as other cereals xi CHIEF KINDS OF FOOD-PLANTS 133 in temperate climates, rye, barley, and oats. In hot climates rice and millet are important. The New World has given maize, or Indian corn — a very important plant now widely distributed. All these are annuals and all require considerable skill to be grown properly, so that it is only relatively advanced people who can grow them on the large scale. Next to these the most important seed-bearing plants are the different kinds of beans and peas. These are not of great importance in a country like our own, where wheat is the chief bread plant and everybody can get a certain amount of meat, but they are very important in countries where little meat is eaten, and especially where such cereals as rice are used instead of wheat. The reason is that beans and peas contain, as we have already seen, a great deal of proteid, and, therefore, they can be used partially to replace meat. If we were to travel down through France, for instance, one of the things we should notice would be the quantities of different kinds of beans that the people grow in their gardens. They grow them as we grow potatoes, and they eat them at one meal in the day at least just as we eat potatoes. If we travelled on into Spain we should find there that a kind of pea, called the chick-pea, is grown everywhere, and largely takes the place of meat. In the same way in China and Japan, where 134 TILLEKS OF THE GEOUND CHAP. the people get very little meat and where they live largely on the rather poor grain rice, they eat a great quantity of what are called soya beans. The rice without the beans would not be enough FIG. 32. — A Rice Farm in Ceylon. for them — they would not get enough proteid. These beans also contain a large amount of fat, which is important because rice has hardly any fat. Thus beans and rice together make a good diet, though neither would be sufficient separately. xi CHIEF KINDS OF FOOD-PLANTS 135 A considerable number of other seed -producing plants are also cultivated, but perhaps we need only mention buckwheat, which is not a true grain, but is used instead of a grain in some places, because it is easily grown, even on poor soil. When we come to consider the plants which man cultivates for the sake of their underground parts, we find that no two families stand out as do the Grass family and the Pea family among seed- producing food-plants. There are, however, a great many families which include one or two useful plants. If we begin with cool climates like our own, we find that the members of the Cabbage family are often important, either directly or indirectly. Thus, if it was not for the different kinds of turnips and swedes, farmers could not keep their sheep alive during the winter, and we could not get mutton to eat. That is, though perhaps turnips do not matter a great deal to us directly, they matter a great deal indirectly. More important to us is the potato, which is the underground stem of a plant of the Deadly Nightshade family. The potato is a plant which likes a cool climate, and requires a great deal less sun than grain does. It is this which makes it so useful a plant in Ireland, where the damp prevents wheat from ripening. It is very interesting to 136 TILLEES OF THE GEOUND CHAP. notice that the potato belongs to a family some members of which are very poisonous. Even the potato itself, if the tubers are allowed to become green by being exposed to the air, becomes unwhole- some and even dangerous. That is why potatoes have to be " earthed up " carefully, and should always be stored in dark places. In hot countries, our potato is replaced by a plant something like it, called the sweet potato, which really belongs to quite a different family, the Convolvulus family. Other plants which in hot countries take the place of our potato in supplying the necessary starch, are manioc and yams. Manioc is an interesting plant. It is a shrub with thick, fleshy roots, which grows easily and rapidly ; so quickly, indeed, that its produce is said to be six times that of wheat. It belongs to the Spurge family, and just as other plants of the potato family are very poisonous, so plants of the Spurge family are also often very poisonous. Even the manioc plant itself is poisonous, and this is a curious and interesting point. We saw before that cooking is generally more necessary for plant foods than for meat, because, without cooking, plant food is often very indigestible. There is, however, another reason for cooking vegetable food, and that is that uncooked vegetables xi CHIEF KINDS OF FOOD-PLANTS 137 are sometimes poisonous. We have all eaten apples, and we have all been told, since we were quite small, that it is not wise to eat apple pips. Suppose we try one, however ; it will not do us much harm, and it is an interesting experiment. If we nibble it slowly between our teeth, we find that our mouths become filled with a nasty-tasting substance. If we eat two or three pips, this nasty taste will perhaps remain in our mouths for several hours, and give us a very uncomfortable sensa- tion. But when apples appear on the table at dinner-time, after having been baked or stewed, we find that the pips have no taste at all, and do not disagree with us. This means that, in. cooking, the heat of the fire has driven off the poison. Now, it is not at all uncommon to find that parts of plants contain poison, which protects them against the attacks of plant-eating animals. But man is cleverer than the animals, and he learnt long ago that poisons could often be driven off by heat. In Brazil the people live very largely on manioc, and it is full of a deadly poison. What do they do ? Well, the roots, the edible parts, are first carefully scraped, then the interior is crushed into a kind of flour, and carefully baked in thin layers, so as to drive off the poison. Prepared in another way manioc makes tapioca, which we eat 138 TILLEES OF THE GEOUND CHAP. in puddings without ever thinking of the poisonous plant from which it comes. Another kind of plant furnishes the yams on which the natives of some warm countries largely depend, and yams again are not wholesome unless they are cooked carefully. In general, we may say that underground stems and roots supply man with a large part of the necessary carbohydrate, but they are deficient in proteid. In cold countries, therefore, they are supplemented both by some kind of seeds and, where possible, by meat. The meat gives the flavour necessary to make the roots digestible and pleasant to the taste. In warm countries, where meat is less necessary, some of the strong vegetable flavouring matters are used usually to make up for the want of taste possessed by the vegetables themselves. In regard to the fruits cultivated by man, we may notice first the great importance of the plants of the Eose family. This family gives us apples, pears, peaches, apricots, plums, cherries, strawberries, and many other of the fruits of warm or cool countries, all of which are wholesome and pleasant, though they do not supply a large amount of actual nutriment. Then "we have in warm countries the vine, a plant of great importance. In this country we think of wine as only a luxury, but in xi CHIEF KINDS OF FOOD-PLANTS 139 countries where less meat is eaten than here, light FIG. 33.— The Vine with Grapes. wine is of great importance, and seems to enable the people to live on less food than they would otherwise require. 140 TILLEES OF THE GEOUKD CHAP. We have already spoken of the great import- ance in hot countries of such fruits as bananas, dates, and figs, all of which contain a considerable amount of food material. We must remember also that vegetable marrows, pumpkins, cucumbers, and so on, are all fruits to the botanist, and these are very useful in warm countries as important additions to the diet. The fruit of the olive tree, again, as we have seen, yields the kind of fat which is most suitable to people in hot climates. CHAPTEE XII IMPROVING CULTIVATED PLANTS WE have already seen that most of our cultivated plants are very old, and that with regard to many, we do not even know from what wild plants they were derived. If, however, the beginnings of these useful plants are very old, we know, on the other hand, that great improvements in them have been made in relatively modern times. Nearly all our cultivated plants now occur in a great number of varieties, fitted for different soils or different countries, yielding different kinds and amounts xii IMPKOVING CULTIVATED PLANTS 141 of produce. It is the existence of these numerous varieties which helps to give the modern so many advantages over the ancient farmer, for he can find some variety fitted to grow on almost any kind of soil. But improvement has not only shown itself in the increasing number of varieties ; it has also shown itself in a general improvement in the different plants. In some cases, especially in fruit trees, where many of the improvements have been very recent, it is easy to prove that this is so. But, though it is less easy, we can also prove that the seed-producing plants have improved greatly since the days when they were first cultivated. There is one rather interesting way in which we may prove this. We have already seen that one of the difficulties in finding out what 'men did in the very early days is that those were the days before writing had been learnt, and man therefore could leave behind him no written memorials to be read by the generations to come. Early man did, however, leave behind him memorials of a sort, and these memorials men of our times have learnt to read, after much stumbling and hesitation. Ages and ages ago primitive man lived in dwellings made of piles at the edges of the lakes in Switzerland and Italy. Kemnants of those ancient dwellings still remain, and from these remnants the 142 TILLERS OF THE GROUND CHAP. life of these ancient peoples has been reconstructed. Though they had only stone tools, these people managed to till the ground and to sow wheat and peas. Though they are long since dead and gone, yet some of the seeds which they dropped have been found, and these have been examined carefully. Even ears of wheat and barley have been preserved, and from these we know that the grains these people cultivated were smaller and poorer than those our farmers now grow. The ears were narrower and shorter, the individual grains smaller, so that the yield of the little plots which they cultivated must have been scanty. By infinite care a Swiss man of science has succeeded in following down through the ages the different kinds of grains in Switzerland. He has shown that the first poor kind of wheat lasted down to the Roman period, when it disappeared for ever. He has shown also how other and better varieties appeared gradually, replacing the old. Thus, by the time the ancient inhabitants of Switzerland had learnt to make tools of bronze instead of stone, they had also learnt to grow better kinds of wheat, especially that called spelt, varieties of which are still grown in parts of Europe. They had also added rye and oats to the poor wheat and barley of the early days. Much the same thing is true of their peas and xii IMPROVING CULTIVATED PLANTS 143 beans. In the remains of the Stone Age, a few traces of a small round garden pea have been found, but it was not until the Bronze Age that this pea seems to have become abundant. In the Bronze Age garden beans appear for the first time, but these were only about half the size of our beans. Not until the time of the Eomans does a larger and better bean appear. When we get down to the time of the Romans, it is easier to show that at least the idea of improving cultivated plants was present to the minds of the people who cultivated the ground. Thus Virgil says : — I've seen the largest seeds, tho' viewed with care, Degenerate, unless th' industrious hand Did yearly cull the largest. This shows that he had noticed that the grains of corn were not all of the same size, and that if even the level already attained was to be kept up, it must be by carefully picking out the best grains to serve as seed-corn. In much the same way, Celsus, who wrote nearly a hundred years after Virgil, but still more than eighteen hundred years ago, says : " Where the corn and crop is but small, we must pick out the best ears of corn, and of them lay up our seed separately by itself." It was not only among the Romans, however, that the farmers saved the best seed for sowing. 144 TILLEKS OF THE GKOUKD CHAP. Very early an Imperial Edict in China recommends that specially large seeds should be sown, in order that a stock of plants producing such seed might be obtained. It is even said that a particular kind of rice, called the imperial rice, was first obtained by the Emperor Khang-hi, who, walking in the fields, noticed a particularly fine rice-plant, and had it brought into his garden. Here it was cultivated and improved, and from this plant a new variety of rice arose, which proved very hardy and very useful. We might go on to show by quotations from early English authors that the method of improving plants, by selecting the seeds of the best plants and sowing these, has been carried on for a long time in England also. What has been already said, however, is enough to show that if our cultivated corn and peas are much better than those grown by the first farmers in Europe — the people of the Stone Age — then this difference is largely due to the steady perseverance of generation after genera- tion of cultivators. But for a reason which we shall have to consider directly, it was not until the eighteenth century that great progress was made. Some of the stories about the discovery of good kinds of cultivated plants read almost like fairy- tales. Thus, a farmer called Hunter, walking in his fields in East Lothian, in Scotland, many years xii IMPKOVING CULTIVATED PLANTS 145 ago, noticed a few ears of wheat which seemed a specially good kind. He carefully pulled the ears when they were ripe, kept the grains separate, and sowed them in a special plot. They grew into plants which had the same good qualities as their parents, and in a few years there was enough seed to put the new variety on the market. Other people found it as useful as Hunter did, and it spread over Scotland and England and even into France, and is called Hunter's wheat to this day. There is another story, even more curious, of a farmer who, for some purpose or other, climbed on the top of a corn-rick. When he came down he found that an ear of corn was sticking to his coat- tail, and that this ear seemed to be specially fine. He saved the seed, sowed it separately, and after several years had the satisfaction, like Mr. Hunter, of being godfather to a new variety. This is one way, then, of making new varieties, by merely picking out from among thousands of ordinary plants the one or two which chance to be exceptional, and breeding from these. This is a slow process, and it was by such a slow process, for the most part, that improvements in seed-producing plants were carried out down almost to the second half of the eighteenth century. Since then a very much quicker, though very laborious, method has been more and more adopted, with the result that L 146 TILLEES OF THE GKOUND CHAP. a tremendous number of improvements have been made. To understand this new method we must go back a little. We have already seen how the Assyrians and the Arabs carried the pollen-bearing branches of the date-palm to the fruit-bearing trees, even though they did not understand clearly the meaning of pollen. The idea of taking away the stamens, or little threads, the swollen tops of which produce the pollen, from a flower which has both stamens and seed-pods, and bringing to it instead pollen from another flower, was much less likely to occur to people ignorant of botany, but yet we have reason to believe that this was done by the Japanese and Chinese very early, and was also to some extent done by the Eomans. When this is done, and when afterwards the seed sets, this seed may grow into plants different from both parents. Very often 'also the seedlings differ a great deal among each other. This crossing, as it is called, is then a way of producing a number of varieties in cultivated plants. In the seventeenth century gardeners in Europe, and especially in Holland, began to cultivate tulips and auriculas, and to produce all sorts of varieties. If we had time we might tell all sorts of curious stories about the tulip mania — how tulip bulbs were sold for their weight in gold ; how men xii IMPEOVING CULTIVATED PLANTS 147 schemed, and quarrelled, and robbed, to get posses- sion of precious kinds ; bow the bulbs had to be watched night and day to prevent the offsets being stolen. These and a great many other curious stories we might tell, but at present it is sufficient for us to know that these wonderful tulips were produced by crossing. The fact was, however, kept a profound secret, and it was not till nearly a century afterwards that crossing came into general use as a means of improving cultivated plants. The " tulip mania," as it was called, was as foolish as most manias, but it did one very important thing — it taught gardeners in general how they might improve their plants ; how they might apply the knowledge that the botanists had been slowly and carefully collecting. In the next chapter we shall have to consider exactly what crossing means, and how it is carried out. In concluding this chapter let us just notice what selection and crossing have done in the case of one cultivated plant, the wheat plant. Wheat, as we have already seen, was originally a cultivated plant of the Mediterranean zone, where the winters are mild and wet, and the summers hot and dry. The plant there was always sown in autumn, grew through the warmth and wet of winter, and ripened in the bright sunshine of summer. But it will not stand a very severe 148 TILLEKS OF THE GROUND CHAP. winter, nor does it do in a very hot dry climate, or FIG. 34.— Different Varieties of Bearded Wheat. with too long spells of dry weather. When it spread over the greater part of the earth, then, it became necessary to have kinds fitted for all the xii IMPROVING CULTIVATED PLANTS 149 different climates. An enormous number of varieties have been produced to meet these needs. It would not be difficult, one author tells us, to name some thousands of different kinds of wheat. The same author describes in detail sixty kinds, which he says are the most important kinds for the farmer in England and France. Things have altered a good deal since the Stone Period, when there were one common kind and four other rare kinds ! The sixty kinds most useful in England and France have all their special properties, and man has to learn, by slow and sometimes painful ex- perience, which kind is most useful in each particular situation. For instance, there is rather an interesting little story about spring wheat in the eastern parts of France. During the terrible war of 1870-71 some of the provinces were so ravaged by war that it was impossible for the peasants to sow their wheat in autumn. By the spring of 1871, how- ever, the war was over, and hope began to revive among the people. One of the most wonderful things, perhaps, in the history of the world is the way in which the French people set to work to repair the fearful destruction which that short war made. Pasteur, the celebrated biologist, was one of the great Frenchmen who set themselves the task of making France great again, not on the field of 150 TILLEKS OF THE GEOUND CHAP. battle, but in the nobler fields of knowledge ; and there were many others. But before a new France could be slowly built up, the people must have bread ; the land swept bare by the two armies must be ploughed and sown. The seed-corn which the peasants had saved had either been eaten in their time of dire distress, or was useless now the springtime had come. So one of the many committees for helping the unfortunate, which had been founded at this time, distributed spring corn (that is, corn which could be sown in spring) in the ravaged provinces. They knew that this spring -sown corn flourished in parts of England, and they hoped that it might do the same in France. But, alas ! they had not noticed the slight difference in climate, the fact that the hot dry summer comes earlier in France than in England, and is both hotter and drier. The hot dry weather came before the wheat had had time to make its growth, and the poor peasants had to stand by and see the empty ears in their fields wither for want of rain. While this happened in France, in England the same wheat grew steadily all through the early part of the summer, which was. damp, and ripened beautifully in August. This little story appears in a French book on the best kinds of wheat, and the only comment the author makes is that this was a lesson to French xii IMPKOVING CULTIVATED PLANTS 151 cultivators in regard to the best times for the sowing of wheat. We must not think from his saying only this that he did not feel the deepest sympathy with his poor fellow-countrymen, all but crushed beneath the weight of their successive misfortunes. He writes as a man of science, and as such fte knows that it is useless to lament over such calamities — the part of the wise is to learn how to prevent them in future. This is the heroic courage which science teaches, not the courage which is only of use on the field of battle, amid the flying of flags and the beating of drums, but that infinitely more precious quality which enables man to see all the results of his work destroyed, and in place of simply giving way to grief and depression, to take from the experience the conclusions which will be valuable to others in future. It is this heroic courage which makes man great, in spite of all his weakness and petti- ness, and one reason why science is so valuable to humanity is that it is the love of knowledge more than anything else, which leads to the development of this particular kind of courage. 152 TILLERS OF THE GROUND CHAP. CHAPTER XIII EXPERIMENTS IN PLANT -BREEDING WE saw in the last chapter that cultivated plants have been improved very greatly since • agriculture began, and that most of them now occur in a great number of varieties. We saw also that in the first place improvements were brought about simply by picking out the best plants and sowing their seeds separately. A good deal of improvement was brought about in this way, but it is a slow and somewhat uncertain method. We saw next that for the last hundred and fifty years or so another method has been more and more adopted. This consists in crossing different kinds of the same or similar plants, these different kinds being sometimes obtained from countries widely separated from one another. The first result of this crossing is often to produce a number of different kinds of seedlings. The next step is to pick out the suitable seedlings, and, by care and cultivation, helped often by fresh crossing, to produce entirely new plants. When making new varieties was merely a matter of picking out good kinds which appeared by xin PLANT-BREEDING 153 chance in the fields, this could be done by ordinary farmers. On the other hand, when these new kinds have to be made deliberately by crossing and then long breeding, there is more work than the ordinary farmer or gardener can undertake. Farmers and gardeners have their daily work to do ; the delicate operations by means of which new plants are now made, require more time and care than they can give. We find, therefore, that now, in addition to the people who grow plants for the sake of their produce, there are other people who grow them for the sake of making new plants, or of producing the kinds of seed best suited to particular conditions. Sometimes these people are nursery-gardeners, who, instead of sending lettuces and cabbages to market, devote themselves chiefly to supplying other gardeners with the best kinds of seeds. There have been in England a number of famous gardeners of this kind, for the production of fine kinds of plants and of farm animals has for long been a speciality of the English people. It is one of the ways in which we show our practical cleverness. In addition to the gardeners, however, a number of other people have worked at this subject, both in this and in other countries. In England espe- cially, there have never been wanting people willing to give their time, their money, and their labour to the experimental study of agriculture and of 154 TILLEES OF THE GEOUND CHAP. methods of plant-breeding. Some of these experi- ments have had for their object the finding out of facts which would be directly useful to the farmer, others have been undertaken in order to learn more about the nature of plants. G. 35. — A Field of Giant Wheat in the New Mexico Experimental Station. But we must not suppose that the latter are really of less use than the former. It has happened again and again that experiments which have been undertaken merely to solve a point of scientific interest have led to the discovery of facts of great practical importance. In the long-run all knowledge is useful, for experience shows that it is the people xin PLANT-BREEDING 155 who are interested in knowing who are successful in doing. We shall consider here, then, first some experi- ments on breeding plants which as yet have had very little practical result. They are an attempt to wrest one of her great secrets from Nature — the secret as to the relation between one generation of plants and the next. When we know that secret, we shall be able to do almost what we will with our cultivated plants and animals, to do it directly, and not with the stumbling slowness which is still the method of to-day. Meanwhile the work of the Abbot Mendel, to which we shall refer directly, is a beautiful example of scientific work, undertaken out of pure love of knowledge, and carried out with that perseverance and single-mindedness which make genuine scientific work truly great, whatever its practical result. Before speaking of Mendel's experiments, how- ever, let us stop to say a few words about the human aspect of scientific work. It is often very difficult for us to understand what scientific work means in the life of the man who does it. We read that so-and-so worked for perhaps ten or twenty years, and at last he arrived at such-and- such results, but we do not realise clearly that it was a human being like ourselves who did all this. We do not see clearly that it was a man who got 156 TILLERS OF THE GROUND CHAP. tired as we get tired, who felt depressed at failure as we feel depressed, who in his inmost heart loved short cuts as we all love them, and had to learn slowly, as we all must learn, that short cuts are generally longer than the weary straight road. When we read that so-and-so produced some useful new plants, or found out some interesting facts, we are apt to think that it must -have been nearly as easy for him to make the new plants or to get the new facts as it is for us to read about them. Before going on, then, to some facts about cultivated plants and how they have been obtained, let us hear a little story about one piece of work and how it was done. It is not a story about plants, but the principle is the same, for it is a story of scientific work, and in principle all scientific work is alike. There was once a doctor — he afterwards became a very famous doctor, but at this time he was just beginning his work. He was not at all satisfied with the way in which doctors treated certain kinds of accidents, and he wanted to improve these ways. For a long, long time he worked, helped by his students, in his workroom, trying to find a better way. At last, after long search, he thought he had found what he was seeking. At this time he had in his hospital a railwayman who had been hurt — badly hurt — in an accident. xiii PLANT-BKEEDING 157 The doctor went to the railwayman, and said to him that he would like to try the new method on his injury. The railwayman was quite willing — he was greatly interested, indeed, for the doctor explained to him just in what way the new method would be better if it succeeded. But if the method failed there was danger. Somebody must always stay by the bedside of the patient, night and day, to make sure that nothing went wrong. Even if a doctor could be got in three minutes it might be too late ; some- body must be always there. Therefore the students — remember they had their daily work to do as usual — arranged to take it in turns to watch by the man's bed night and day, with all their instru- ments ready, so that if anything went wrong, it could be put right instantly. For ten days, the doctor said, there would be risk. For ten days the man must never be left for an instant. Nine days passed, and everything went well. Every morning the doctor came, and every morning the patient said, " It's holding, doctor," for he was as keen as anybody on the experiment. But, alas ! during the ninth day something went wrong. A watchful student was at hand, and no harm came to the brave patient — but the doctor had failed. What he felt, nobody knew ; but one of his students says that he came into the lecture-room next morning exactly the same as usual, and he 158 TILLERS OF THE GKOUND CHAP. said, " Gentlemen, this experiment has failed. We must begin over again." Success came afterwards ; it must come with such a man, but this same student says that he never forgot the courage and the dignity of that little speech. " We have failed ; we must begin again." Is not man truly great when he can say that, when he can .begin again — begin the very day of his failure ? Now in the short accounts of scientific work for which alone we have room here, we can only speak of the results, of the successes, but we must not on that account think that there was no failure. Just as we fail, fail constantly, so all the great men have had times of failure. What makes them great is that they have had the courage to begin again, which we do not always have. The love of know- ledge will carry man farther than almost any other quality ; it carries him through failure to victory, and the victory is often not for himself but for those who live in the future. With this little story in our minds to help us to understand what scientific work means in the life of the man who does it, let us cross the Channel and travel across the continent of Europe to Austria, in order to learn something about the experiments of the Abbot Mendel. Mendel was born in Silesia, and was the son of xni PLANT-BKEEDING 159 country folk, so that from boyhood he was probably interested in country things. But he was a clever boy, and as his parents were not poor, it was decided he should go into the Church. He studied science at Vienna, and afterwards became Abbot of Brlinn, a town in Moravia in Austria. Though he did some teaching at one time, we must suppose that Mendel had a good deal of leisure, and his monastery had evidently a large garden. He was especially interested in crossing, and what he wanted to find out was exactly what happened when plants were crossed. We have already spoken of the meaning of crossing in a general way. Let us note just what it means in the case of one particular plant. We may find in a garden tall peas, which need to be sticked, and short peas, or dwarfs, which do not need to be sticked. Each pea-flower, whether borne on' tall or dwarf peas, contains both stamens, or pollen-containing organs, and a seed-pod. Usually the pollen from these stamens falls upon the seed- pod of the same flower. That is, the flower is what is called self -fertilised. But suppose we take away all the stamens from the flower of a dwarf pea, and drop carefully on the top of the seed-pod some pollen from the flower of a tall pea, then we may say that we have crossed the dwarf pea and the tall pea. 160 TILLEES OF THE GBOUND CHAP. The next point is, suppose we sow the seeds from the pod formed in this way, shall we get tall peas or short peas ? Or shall we get both short and tall peas ? That was the kind of question that Mendel set himself to answer. Gardeners and others who work at these questions find it convenient to have a word to signify the plants which result from a crossing. When- we go to a flower show we quite often find a flower or a vege- table labelled so-and-so's new kybrid-TOBQ or new hybrid-cabbage. The word hybrid means that the plant has been produced by crossing two varieties of plants. Using this convenient word " hybrid," then, we may state more exactly what Mendel wanted to do. He wanted to cross two kinds of plants, differing from one another in one or a few clearly marked features, and then to sow all the seed obtained in order to try to find out the exact propor- tions in which the parent plants would appear in the hybrids. But we are not really so very much concerned here as to what he wanted to find out, as to under- stand what he did, in order to understand what crossing and breeding means. The first thing was to find suitable plants for his experiments. After some time he decided that the Pea family was the best, and after growing XIII PLANT-BKEEDING 161 different kinds of plants for some time, he decided that the garden pea was the best of this family for his purpose. BBBBBHBHBBBHBB FIG. 36. — The crossing of different kinds of Wheat. The middle figure represents a hybrid form produced by crossing the kinds shown to right and left. But though these experiments were carried out about fifty years ago, there were even then a great many different kinds of garden peas. There are still more now. Mendel got from a seedsman thirty-four M 162 TILLEES OF THE GKOUND CHAP. kinds of peas, and grew them all for two years, to see which suited him best. Of these he decided that twenty-two kinds were suitable; these twenty-two he grew during the whole period of his experiment. We should try to think what this means. Mendel tells about it so simply and so naturally, that one would suppose that to grow twenty-two different kinds of peas and keep them all separate was the most natural and simple thing in the world. He then goes on to tell about his experiments -after the two years of preliminary work. He made seven different sets of experiments, and these seven .sets of experiments involved the fertilisation of two hundred and eighty-seven flowers. Each of those two hundred and eighty-seven flowers was opened while it was still in bud. From each of those buds the ten stamens were delicately picked out with a pair of fine forceps. On the seed-pods of each one of those two hundred and eighty -seven flowers, pollen from another flower was placed. Each one •of the flowers so crossed was then covered up so as to prevent insects bringing any other pollen to them. This was the beginning of Mendel's experiment. It was also only the main experiment, and does not include all the extra observations that had to be made to be sure that all was going right. He speaks quite simply of examining carefully ten xin PLANT-BKEEDING 163 thousand plants to be sure that his experiments were not being spoiled by bees visiting the flowers and carrying strange pollen ! From the two hundred and eighty-seven flowers that he crossed Mendel got a great deal of seed. This seed was very carefully sown, every grain of it, in carefully marked beds. The plants raised in this way were allowed to fertilise themselves, and their seed again sown. This was repeated for four, five, or six years, the peculiarities of the plants raised each year being observed very carefully, and an exact count kept of the numbers of different kinds of plants. We cannot stop here to explain exactly the results Mendel got, one or two points only can be mentioned. Thus in the experiments of crossing tall and short peas, he found that the hybrids, that is the plants obtained by crossing, had all long stems, longer even than that of the parent long- stemmed plant. This is a very curious point. But when their seeds were again sown, it was found that in the next generation some of the plants were short - stemmed, i.e. were like their grandmothers, and others were long-stemmed like* their parents. The proportionate number of short and long stemmed plants was also always constant. There is no doubt that Mendel's experiments are very important in connection with explaining 166 TILLEES OF THE GKOUND CHAP. In the first place, living in California, he enjoys more advantages of climate than European gardeners. In Holland, in England, in France, etc., the climate is much less favourable, and, therefore, gardeners have had many difficulties which do not present themselves in California. Secondly, for a variety of reasons, Burbank has been able to do his work on a very large scale, and that enables him to get results faster than those who have had to work with fewer advantages. Let us begin with the very simple little story of the Californian poppy, which at least shows the methods employed. In California a pure yellow, wild poppy grows abundantly all over the hillsides. Looking at a great number of these wild poppies one day, Mr. Burbank noticed one that had a crimson line on the yellow petals. This plant was carefully trans- planted, and grown by itself in a nursery bed. At the end of the flowering season its seeds were saved, and these seeds were sown in a special bed. When the seedlings flowered in their turn the next season it was found that some had a slightly wider red band, while others again were pure yellow. The pure yellows were what the gardeners call " rogued," that is, ruthlessly pulled up and burnt, while seeds were saved from those with the broadest red band. This process went on for many genera- XIV MAKING NEW PLANTS 16T tions, the plants with the reddest flowers being chosen each season and the others rejected. In the long run a pure crimson poppy was produced in this way. Very similar to this is the story of the Iceland poppy, of which several garden varieties were FIG. 37. — The Botanist, de Vries, in his Greenhouse. produced by Miss Gertrude Jekyll, an English lady much interested in plants. Miss Jekyll grew a plant of the yellow Iceland poppy in her garden, and as it was a new garden flower, she sowed a great deal of the seed. The flowers of the seedlings were not all quite the same colour ; some had a slightly orange tint. By selecting the seed care- 168 TILLERS OF THE GBOUND CHAP. fully, for several years, white, lemon, yellow, and buff varieties were obtained, and these varieties are now grown in every garden. Here is another experiment, rather a pretty one, which was carried out by the great Dutch botanist called de Vries. He was out one day on an ex- cursion in Holland, his native country, and he had, as he puts it, the great good-luck to find two " four- leaved " clover plants. Perhaps somebody here has looked for these plants without de Vries' good fortune. At least, we all know that these plants, like " even- leaved " ashes, bring good -luck to the finder. Some of us, perhaps, if we have never found a four-leaved clover have found the commoner " even ash." We know that if a girl finds such an ash, she has only to go out into the road, singing — An even ash I now possess, new plucked from the tree, The first young man that I shall meet, my own true love shall be, and then she will be happy ever after, just as in a fairy tale. Well, it is not probable that de Yries wanted to use his four-leaved clovers for magic, either black or white. Let us see what he did do with them. He brought the precious plants home into his garden, and there cultivated them for " three long years," says the original. He had the satisfaction XIV MAKING NEW PLANTS 169 of finding that as a result of his care the number of leaves with four parts increased. He then collected the seed of the plants and sowed it. He got a number of plants which showed a slight increase in the num- ber of leaves with extra parts. Out of this bed he picked out the four plants which had the highest number of four - partite leaves and saved their seeds. All the other plants were destroyed. He went on in this way for nine generations. The results were curious. In the plants with which de Vries began there were many three-partite leaves FIG. 38. -A piece of de Vries' (that is the USUal kind), Clover, with four-, five-, and . . . six-partite leaves. several lour - partite ones, and one with five parts. By going on always taking the seeds of those plants with leaves having more than three parts, he succeeded in producing clover plants with four-, five-, six-, and seven-partite leaves. In the end his clover bed contained plants the leaves of which had mostly five 170 TILLERS OF THE GROUND CHAP. parts. There were always a few three -partite leaves, as well as four-, six-, and seven-partite ones. Perhaps somebody will say that five -leaved clovers are not much use, especially for people who do not believe in "luck." But is it not rather interesting to know that with time and patience we can make almost any plant we want ? These cases illustrate what can be done by simple selection, accompanied by careful cultivation. Let us take now another case to illustrate what crossing does. Burbank has done a great deal of experi- menting with the different kinds of lilies, which are such favourite garden flowers. He wanted to produce a number of new varieties, and to get these he began in this way. He got, from all parts of the world, nearly fifty kinds of lilies, all of which had in his eyes some particular merit which made them good, though not perfect, garden flowers. These lilies were crossed and intercrossed in the most elaborate way, a long series of experiments being performed. The result was a large amount of hybrid seed. This seed was sown, and finally as many as a hundred thousand hybrid lily plants were produced. Two acres of ground were planted out with these lilies, and all were allowed to flower. The result of the crossing was such that among these hundred thousand plants almost every possible variety of lily xiv MAKING NEW PLANTS 171 was to be found. Some were purely fantastic, with no special beauty ; others had beauties not present in any one of the original lilies, but produced by the process of hybridisation. This was the first step, the crossing. The next step was, of course, the selection of the best kinds. The fields of lilies had to be gone over with pains- taking care. All the useless or ugly plants were pulled up and burnt without mercy. Quite often among these hybrids would be found one which had some particular merit, perhaps colour or perfume, and at the same time some undesirable character, such as a stalk too weak to carry the flower head, an unsymmetrical flower, and so on. In these cases it was necessary to recross with another lily, in the hope of getting new -hybrids which had all the merits and none of the dis- advantages. This recrossing had, of course, again to be followed by fresh cultivation and selection. In this way more than a million lily bulbs were grown, and the final result was that some two hundred and fifty thousand distinct lily hybrids were produced as the result of the experiments. Only some of these were, however, useful. These cases show us what the gardener can do by culti- vation, crossing, and selection to improve plants. But it is not sufficient to produce a new variety; it is necessary to produce it on such a 172 TILLERS OF THE GROUND CHAP. scale that it can be supplied to many people. One great advantage of such plants as the lilies is that once a desirable kind has been produced, it may be increased by means of its bulbs, instead of FIG. 39. — One of the improved prickly pears with large fruits pro- duced by Mr. Burbank. The plant is four years old, eight feet high, and bears over 400 pounds of fruit. Half of one leaf put in the ground in April produced over sixty leaves by the middle of September. only by seed. This is a great advantage, because improved plants which can only be reproduced by seed show a great tendency to " run back " to the original stock. On the other hand, when they can be reproduced by a part of the original stock, such as a bulb, a cutting, a tuber, as in the xiv MAKING NEW PLANTS 173 potato, they " keep true," that is, do not change in character. Most of our cultivated plants, except where the seeds are the edible part, are reproduced by some part of the parent plant, or, as the botanists say, " vegetatively." This is a method which has many advantages. Take the potato, for example. It is possible, by the crossing and selection process which we have described, to make a new variety of potato, which will combine merits found hitherto in separate kinds. That is to say, it may be hardy like one parent, and very early or very prolific like the other. Now, if this potato had to be grown from seed each year, not only would the process be much slower than the present way, where a piece of potato is put into the ground, but also the seed- lings would not be all alike. Some would have kept their hardiness, but lost the power of ripening early. Others would be ready early, but would be delicate, and so on. This means that though man can make almost any kind of plant he likes, if he has patience enough, yet it is very difficult for him to give his " creations " the power of lasting, the stability which natural plants have. In Nature, plants are generally very like their parents, they are generally stable. By cultivation, and especially by crossing, man can easily destroy this stability. He can, as 174 TILLEES OF THE GKOUND CHAP. it were, make the plants rock to and fro instead of keeping steady. What he always wants to do is to stop them when they have moved just to the point that suits him, and that is the difficulty. When they have reached that point they either go on, or else they seem to want to come back to the point they started from. They seem to remember the peculiarities of their ancestors, and to feel a kind of homesickness to be back to the point they started from. Perhaps this may seem a fanciful way of putting the matter, but, however we put it, it is of the greatest importance to us. Civilised man prospers and multiplies because, by working through long ages, he has succeeded in producing all sorts of wonderful plants, which feed and clothe him. But those plants, cultivated and improved by man for a few thousand years only, go back as wild plants into the inconceivably distant past. In their cells and fibres they have memories of the time before man was ; let civilised man slacken his grip never so little, and they will slip back into their ancient ways. They will become poisonous, or unwhole- some ; their seeds will grow small, their fruits bitter, their roots will become tough and fibrous again, and so on. When we read that man started to cultivate plants thousands of years ago, that he has been XIV MAKING NEW PLANTS 175 successful in improving them during long genera- tions, we are apt to think that the work is practically done, that we need only enjoy what our fathers have done for us. But it is not so. Our FIG. 40.— Gathering Wild Prickly Pear Fruit in Mexico, where the plant is native. inheritance is like the magic gold in the fairy tales. If we do not use it aright it will turn into a mere handful of withered leaves, and leave us poorer than we were before we got it. We know that Cinderella's beautiful coach was 176 TILLEKS OF THE GEOUND CHAP. made out of a pumpkin, and changed back into a pumpkin as soon as the clock struck twelve. Well, our apples and pears, all our garden fruits and flowers and vegetables, indeed, were made out of poor, useless, wild plants, arid the moment we cease to try to keep on improving them, they will begin to slip back into their original state. The change is not so sudden as in the fairy tales, but it is just as real. One other point about improving cultivated plants is important. We have just seen that in the case of plants produced from seed, there is always the risk that the seedlings will not have all the good qualities of their parents, a risk which does not exist when the plants are reproduced vegetatively. But plants which are always repro- duced from seeds are at least frequently annuals, and they have the great advantage of quick growth. There are some grains which can be sown and harvested within a period of three months. In warm countries, if there is enough water, more than one crop of these plants can be raised in the year. The result of this is that improvements can be made rapidly. On the other hand, when plants are not annuals, they very frequently take several years, sometimes many years, to come to flowering age, and in that case improvement by crossing must be XIV MAKING NEW PLANTS 177 a slow process. Mr. Burbank spent twenty-six years over his lily experiments — a very long time ! The reason was that after he had crossed his lilies he had to wait till they flowered before he could see the result, and lilies grown from seed do not flower for some years. Once they got to flowering size he did not need to sow seed again, for he could use the little bulbs, but he had to wait a long time till they did flower. All this simply means that when plants are annuals and are multiplied by seed, they can be improved com- paratively quickly, but the improve- ments are not always constant — the process of selection has to be kept up. When plants are reproduced vegetatively, and are perennials, it takes longer to improve them, but the improvements are more constant. In the improvement of fruit trees, which often only grow very slowly to maturity, the process of grafting has played a great part. Grafting is certainly old, but it is now carried on on an N FIG. 41. — How Grafting is effected. 178 TILLEES OF THE GROUND CHAP. extensive scale, and can be used to make the improvement of cultivated plants much more rapid. Grafting means the fastening of a little branch of a valuable tree to a branch of a less valuable tree. If it is properly done, the graft, or scion, joins completely to the tree or stock, and grows as if it were part of it. It is usual to cut away all the branches of the stock, so that all the food absorbed by its roots goes into the graft, which then produces flowers and fruit. CHAPTER XV THE STRUGGLE WITH DISEASE WE have seen that, ages and ages ago, man picked out certain plants which were worth cultivation, and began to grow these with special care. We saw next that this was done only at certain places on the surface of the earth, and that the people in other parts were for the most part content to borrow these plants, which in this way gradually spread over the earth. We saw also that this spreading process is now going on at perhaps a faster rate than ever it did before, with the result that the earth is year by year producing more food for man. xv STEUGGLE WITH DISEASE 179 Then we saw that, partly as a more or less unconscious result of cultivation, and partly by deliberate effort, man has been, and is, improving his plants, so that they become better fitted for new countries, so that they produce more and more abundantly. But this is not nearly all ; we have still to consider what is in some ways the most interesting point about the cultivated plants — the desperate struggle man has had to wage with plant diseases. We have seen already what wonderful things he has done. He has toiled continuously to wrest her secrets from Nature, and, with every problem he has solved, he has become more skilful in bending her to his will. But it is not an easy task, and every now and then Nature takes her revenge on a big scale. Man brings the potato from America to Ireland, where wheat grows badly because of the damp climate. Here the potato grows abundantly, and becomes the staple diet of many of the people. Then Nature rebels, and sends a deadly disease ; the potatoes are blackened and destroyed, and thousands of people are brought suddenly within sight of starvation. For thousands of years man grows the vine superbly in the sunny parts of Europe, until the skill of the cultivators becomes a proverb, and the wine is world-famous. Then an insignificant little 180 TILLEES OF THE GEOUND CHAP. parasite is introduced by chance from America ; it attacks the carefully kept vineyards, and whole communities are half ruined. These are only two cases out of many, two out- standing cases ; but all through his history as a cultivator man has had to keep up this ceaseless struggle. It is a struggle in which he cannot stop to rest for an instant, a heroic struggle which has made many heroes. It is the green plants only which can bring from the sun's rays the energy necessary for life, and therefore man must grow green plants, or die. It is the starch and sugar which the green plants make which enable us to use our muscles. It is the green plants which form the coal which moves our machines. In the long-run, it is the green plant which moves the whole world of living things, and therefore the battle of the green plant is our battle. The potato disease, the vine disease, the wheat blight are so many threats against our supremacy ; we must conquer them or perish. We have read how Adam in the Garden of Eden was given dominion over the beasts of the earth, " over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth " ; but over the enemies of his cultivated plants he was not given dominion, that xv STKUGGLE WITH DISEASE 181 he has had to conquer slowly for himself — and the battle is not yet won. It is a battle compared with which the struggle with wild animals is as nothing. Saul may have slain his thousands, but David has slain his ten thousands. But just because the struggle has been so fierce, FIG. 42. — Mildew, a fungus which causes a destructive disease on the leaf and iruit of the vine. it has taught man much. We have already read the little story of the great doctor who was prepared to begin again the moment he found that his past work had failed. In the struggle with plant disease, also, a remedy must be found, and therefore man must learn to reap success through failure. While men and women and children are dying of famine, others must be toiling to find a cure for 182 TILLEES OF THE GKOUND CHAP. the disease. Sympathy and charity are not sufficient ; some members of the community must look beyond the needs of the moment to the future. This is one thing that the struggle with disease has taught. One other point is as important. We some- times hear people say that " science " is no use, that the practical farmer or gardener knows far better how plants should be grown than the agricultural chemist or botanist, and that it is only the practical man who has any right to speak on the subject. But when a terrible disease comes the practical man, who depends for his daily bread on his fields, is often almost crushed by the calamity. It is so near to him that he is reduced to despair. " What good will it do," he is inclined to say, " to pull up my blackened potatoes, and see what is really wrong ? They are useless, and I am ruined, and that is the end of it all." It is when this happens that the man of science can step in, and say, " Courage ! it is not so bad as you think ; we can help, we can perhaps prevent the same thing happening again ; we can show you how to reduce the loss as much as possible." One of the uses of men of science is to prevent despair at critical moments. Very often they can do it just because, while the farmers have been growing potatoes and wheat and so on, they xv STRUGGLE WITH DISEASE 183 have been studying all sorts of little problems which at first sight do not seem to have any practical use at all, but which give them a know- ledge of the conditions of life of plants which they could not get in any other way. They have, therefore, a starting-point from which they can proceed at once to study the new problem of the disease. In order to understand just what the struggle with disease means, we shall take one case in a little detail, that of the mildew or blight of wheat. This disease, to which the names of rust, mildew, and blight are all given, is very old, for it was known to the ancient Greeks, who had observed its ravages in their corn-fields. They thought the cause was the anger of the gods, and accepted it as one of the inevitable evils of life. Similarly, the Romans were quite familiar with the disease, which they thought was due to a particular goddess, to whom they offered sacrifices in order to avert her unwelcome attentions from their crops. Pliny, some of whose curious opinions we have already considered, speaks a good deal of mildew, and what he says is very interesting. He begins by saying that it is due to " the inclemency of the weather," and goes on to say that " it attacks corn most frequently in localities which are exposed to dews, and in valleys which have not a thorough 184 TILLEES OF THE GKOUND CHAP. draught for the wind ; windy or elevated spots, on the other hand, are totally exempt from it." Now if this is not a very satisfactory explana- tion, it has at least an appearance of common-sense. But, and this is a curious point, he goes on to give other causes of mildew. The moon, he is disposed to think, has something to do with it, then there is something which falls from the Milky Way, which, he thinks, must be taken into consideration. Finally, there is the Dog-star belonging to " a con- stellation baneful in itself, and to appease which a young dog should first be sacrificed " ! If the blight attacks the vines, then " three crabs " should be burnt among the trees on which the vines are trained. Now it does not do for us to laugh too much at Pliny, for people believed very foolish things until long after his day, and the people of the future will probably think that we believe things just as foolish as the usefulness of sacrificing a " young dog." It is much better to try to find out exactly what the people in Pliny's time really thought. It is clear that by this time they had noticed that fields which were more or less constantly damp, either because they lay in hollows, or because they were surrounded by high walls, were more likely to be attacked by mildew than corn grown in exposed places, and also that damp weather increased mildew. xv STRUGGLE WITH DISEASE 185 Therefore, one party said that it was the damp which caused mildew, just as until lately people said that damp caused ague and marsh fever and malaria. We know now that these diseases are caused not by the damp, but by a minute organism which is carried from one person to another by mosquitoes, and that mildew is due to a fungus. But in Pliny's time, in addition to the people who reasoned sufficiently to see that there was some connection between damp and mildew, there were other people who did not reason at all. They saw that mildew appeared in their crops in spring- time, and they looked for the cause, not on the earth, but in the changes which were taking place in the sky at this season. To please these people Pliny gave instructions about the crabs and the young dog. Let us take a long jump in time from Pliny and come down to the nineteenth century. In a little book published in 1846 (not so very long ago !) we read that blight and mildew have " three distinct and dissimilar causes." These are " cold and frosty winds, sultry and pestilential vapours, and the propagation of a parasitical fungus." The difference from Pliny's statements is not so great as it seems at first sight. This author adds a fungus as a cause, but he mentions that last. He does not tell us where the sultry and pestilential 186 TILLERS OF THE GKOUND CHAP. vapours come from, whereas Pliny thought they came from the Dog-star, but these are the chief differences between the two. If, instead of taking a plant disease, we had taken such a disease as malaria we should have found almost the same thing ; that is, that for many hundreds of years practically no progress had been made in determining the exact cause of the disease. It is a minute animal parasite which causes malaria, and it is a plant parasite which causes mildew in wheat, but in neither case could progress be made until other sciences had advanced. Before minute parasites can be studied we must have powerful microscopes, and it took a very long time to find out how these could be made. Once again, a very great deal of the progress which has been made in recent years in finding out the causes of disease, has been due to the fact that men of science have a great number of dyes at their disposal to colour the minute animals and plants which cause disease. Even with very good micro- scopes it would not be possible to find out the details of the structure of these parasites, if it were not possible to " stain " them, as it is called, with certain dyes. Now most of these dyes are what are called " aniline dyes," which are obtained from coal-tar, and it was only in the middle of last century that these dyes were discovered. XV STKUGGLE WITH DISEASE 187 This is an interesting little fact because it helps to show us how all science, that is all knowledge, is linked together. We can- not hope to learn every- thing there is to know, we cannot e.ven hope to be interested in all know- ledge, but it is wise to learn to respect all know- ledge, just because of this fact that it has always been found that one dis- covery fits into another like the pieces of a picture puzzle. It is a very far FlG- 43._A Section of a Potato cry from mildew in wheat to the discovery of the aniline dyes, and yet without the aid of those dyes the botanists could never have found out all that they have found about the minute plants which produce mildew. Leaf, attacked by the fungus which causes potato disease (much magnified). a is the under surface of the leaf, which has pores (st.) through which the fungus enters, b shows the loose tissue of the leaf through which the fungus threads (in) spread. The spores (c) project on stalks from the surface of the leaf, and are carried by the wind to other potato plants, so that' the disease is very in- fectious. Knowing also is the first step towards curing, and it is a big step. We have spoken of the ruin which such plant 188 TILLERS OF THE GROUND CHAP. diseases as potato disease or the vine disease have brought, but these are diseases which have appeared suddenly, like the dreadful epidemics of plague or cholera which sometimes sweep over a country. Wheat-rust has been with man probably ever since he began to cultivate wheat. Sometimes it appears in a very bad form, and is then especially destructive, but it is always present to a greater or less degree. Perhaps some one then may ask, Does it really do much harm ? Is it worth all the botanists' toil to find out the cause and the cure ? Here are two sets of numbers which may help to answer this question. In Australia a great deal of wheat is grown. In that country there are now nearly four million people. It is estimated that there the annual yearly money loss from wheat-rust is between two and three million pounds. That is, every year, every man, woman, and child in Australia, supposing the loss to be equally divided, would lose between ten and fifteen shillings from wheat-rust alone. In Prussia in 1891, which was a very bad year for rust, it was officially estimated that the loss to the com- munity from the disease was twenty million pounds. We can see from these figures that it is very well worth while to try and find a cure for rust. Have we not all cause to be grateful to the people who have toiled to explain the why and the wherefore xv STEUGGLE WITH DISEASE 189 of those insignificant black or rust-coloured stripes which occur on the leaves of corn and other grasses ? We must remember also to include in our gratitude not only the individual people who have worked at this particular subject, but all the innumerable people who, quite often without in- tending it, have made the work of the others possible. The opticians who worked at improving microscopes, the chemists who made the dyes, we have already mentioned, but these are only two sets of people ; it took a great number of other workers before the exact cause of rust in wheat could be explained. Even yet there is still a great deal to be done, for it is not possible to prescribe a cure, though it is possible to suggest ways of diminishing the risk of infection. But it is clear, is it not, that knowledge does not come merely with the lapse of time ? We haye seen that for 1800 years after Pliny not much progress was made. Progress comes when in a community there are a number of men, with different types of mind, who are willing to devote themselves to the search for knowledge. Each may only succeed in doing very little, but the next generation can stand on the platform they have built, and so rise to heights they never dreamt of. 190 TILLEES OF THE GEOUND CHAP. CHAPTEE XVI THE STORY OF RUST IN WHEAT How can we recognise the disease variously known as blight, rust, and mildew ? Suppose we examine in summer-time a field of wheat, oats, 'or rye, or even a meadow full of grass. Especially if the summer has been a damp one, we shall find quite likely that some of the plants have long, rusty- brown streaks on the stems and leaves. These streaks are like rust not only in colour but also in the fact that we can rub off a red powder. Later in the season we may find, instead of these rusty streaks, black or very dark streaks, which blacken the fingers, just as the other kind reddened them. The first stage is the rust stage and the second the mildew stage of wheat disease. (See the diagrams on p. 198). The next point to be considered is, what harm does the rust or mildew do to the wheat plant ? This is very readily explained. The black or brown streaks on the leaves mean that the substance of the leaf is largely destroyed. Now it is by the leaves that the plant makes the starch which so largely fills the grain. The presence of the streaks xvi STORY OF RUST IN WHEAT 191 therefore means that the plant has less power of starch-making, and therefore the grains are small and light. That the cause of these streaks was a fungus was known some centuries ago, and as soon as the development of the microscope permitted, it was recognised that the powder on the infected plants was what the older botanists called the " seeds " of the fungus, and what the modern ones call spores. That by these spores fresh plants could be infected was an obvious conclusion, which was drawn com- paratively early. For instance, Sir Joseph Banks, writing in 1805 for English farmers, gives the following account of what was then known as the fungus. He does not, we must remember, profess to put forward anything new about the fungus, but simply to tell farmers what the botanists thought at this time. He begins by explaining that on the surface of the leaves and stems of the grasses there are minute pores. He regards these pores as a means of taking in water, for he says : " A plant cannot when thirsty go to the brook and drink, but it can open innumerable orifices for the reception of every degree of moisture, which either falls in the shape of rain and dew, or is separated from the mass of water always held in solution by the atmosphere ; it seldom happens in the driest season that the night 192 TILLEKS OF THE GKOUND CHAP. does not afford some refreshment of this kind, to restore the moisture that has been exhausted by the heats of the previous day." We know now that Sir Joseph was wrong in thinking that the use of the pores on the leaves of plants is to allow them to take in water. It is the roots which take in water, and the leaf-pores allow the surplus to escape, besides having other uses. He was, however, perfectly right in believing that it was through these pores that the fungus found an entrance. Here is his account of the process, which is rather interesting : — " By these pores, which exist also on the leaves and glumes [that is, the scales on the ears], it is presumed that the seeds of the fungus gain ad- mission, and at the bottom of the hollows to which they lead, they germinate and push their minute roots, no doubt (though these have not yet been traced), into the cellular tissue beyond the bark, where they draw their nourishment, by intercept- ing the sap that was intended by nature for the nutriment of the grain ; the corn, of course, becomes shrivelled in proportion as the fungi are more or less numerous on the plant ; and as the kernel only is abstracted from the grain, while the cortical part remains undiminished, the proportion of flour to bran in blighted corn is always reduced in the same degree as the corn is made light. Some corn of this xvi STORY OF BUST IN WHEAT 193 year's crop will not yield a stone of flour from a sack of wheat ; and it is not impossible that in some cases the corn has been so completely robbed of its flour by the fungus, that if the proprietor should choose to incur the expense of thrashing and grinding it, bran would be the produce, with scarce an atom of flour for each grain." Sir Joseph Banks goes on to say : " Though diligent inquiry was made during the last autumn, no information of importance relative to the origin or the progress of the blight could be obtained : this is not to be wondered at ; for as no one of the persons applied to had any knowledge of the real cause of the malady, none of them could direct their curiosity in a proper channel." He then proceeds to explain that the corn seems to become infected in spring or early summer, and that the streaks are first orange, and later, as the straw ripens, become chocolate-brown. He knew also that what he calls the " seeds " of the fungus are produced in great numbers, and are very light, so that they could be carried easily by the wind, but he was puzzled as to what became of the fungus during the rest of the year, and how it reached the wheat in late spring. But there was at least one direction in which it was hopeful to look for an explanation. During the whole of the preceding century, that is the o 194 TILLERS OF THE GROUND CHAP. eighteenth, the farmers had been getting more and more convinced, that, absurd as the suggestion may seem at first sight, the common barberry bush had something to do with blight. " It has long been admitted by farmers," Banks says, " though scarcely credited by botanists, that wheat in the neighbour- hood of a barberry bush seldom escapes the blight. The village of Rollesby in Norfolk, where barberries abound and wheat seldom succeeds, is called by the opprobrious appellation of Mildew Rollesby." Another example which he might have given was that some fifty years earlier, in 1755, the farmers of Massachusetts were so convinced of the connection between barberry and rust that they succeeded in getting a law passed to order the rooting up of the barberry bushes, because of their bad effect in occasioning the " Blasting of Wheat and other English Grain." The difficulty was, however, that when asked why they thought that barberries produced mildew, the farmers could only reply feebly that barberry pollen was yellow, and rust was yellow to begin with, and perhaps it was the yellow barberry pollen that fell on the wheat and made the rust ! It was much the same story as that of Mohammed and the date-palms over again. Nobody could give Mohammed any intelligible reason why branches of wild dates should be hung over the date trees in XYI STOEY OF BUST IN WHEAT 195 the gardens, and the farmers could give no in- telligible reason why barberry bushes were bad for corn, but the Arabs arid the farmers were right and Mohammed and the botanists wrong none the less. Sir Joseph Banks felt that if the farmers were right about the barberries there must be some reason, and therefore he offers one. " It is," he says, " notorious to all botanical observers that the leaves of the barberry are very subject to the attack of a yellow parasitic fungus, larger, but otherwise much resembling the rust in corn. " Is it not more than possible that the parasitic fungus of the barberry and that of wheat are one and the same species, and that the seed transferred from the barberry to the corn is one cause of the disease ? " We notice that Sir Joseph Banks only suggests this as one cause of the disease, his idea evidently being that the fungus could grow indiscriminately on barberry and wheat. There is added to his paper as an appendix a letter from Mr. T. A. Knight, who was a distinguished agriculturist living at this time. In this letter Mr. Knight details some experiments which he had performed to try to find out whether the fungus found on barberry had anything to do with wheat blight. He succeeded in showing that wheat sown round an infected barberry bush all became infected with blight by 196 TILLERS OF THE GROUND CHAP. the beginning of July, up to which time the plants remained free from disease. He found also that wheat plants at a distance from the barberry bush remained permanently free from disease, showing that the weather in itself did not affect the question of blight or no blight. He also showed that wheat plants free of blight could be infected artificially by bringing branches of barberry with fungus on them close to the wheat plants. But his experiments were performed in what a botanist would call rather a haphazard fashion, and therefore they left him in some un- certainty as to whether damp had not at least as much to do with the disease as the fungus on barberry. A few years later a Danish schoolmaster, called Schoeler, carried out some further experiments which made the connection between the barberry fungus and the blight in wheat more certain. At the same time, however, it was not clear exactly what was the exact relation between the two ; quite a number of people therefore persisted in saying that the idea that barberry bushes in the hedges were bad for wheat-fields was merely an idle tale. As in so many other cases it was not possible to solve the problem completely until some other questions, apparently not nearly related, had also been solved. It was not sufficient to study rust in xvi STOEY OF BUST IN WHEAT 197 wheat alone ; much had to be learnt about fungi in general, before this particular fungus could be understood. We find, therefore, that the next stage in the study of rust was one which did not seem to have anything at all to do with that particular disease. About the middle of the nineteenth century a French botanist called Tulasne began to study fungi carefully, and he soon discovered a curious fact. This was that quite a number of fungi occur in different forms and on different plants. Let us think what this means. A primrose growing in a wood and a primrose in a garden are both primroses, even if the garden one is larger or finer, or in some way slightly different from the wild one. But there are many fungi which can grow in different situations, or on different plants, and then they are so different in appearance that no one would believe, without proof, that they had any connection with one another. Tulasne showed that there were a great number of cases of this kind. Now it is very easy to show that the fungus on the barberry is very different from the rust of wheat, but Tulasne's work showed that this differ- ence did not make it impossible that the two were nearly related. The next step was actually to follow the history of the rust throughout the year, to see exactly 198 TILLERS OF THE GKOUND CHAP. what position the fungus on the barberry occupied. This was finally done in 1865 by a German botanist called de Bary, who grew the little spores both on wheat and on barberry, and followed out com- pletely what the botanists call their life-history. FIG. 44. — Diagrams showing Rust in Wheat. A and B, stems of wheat showing the streaks of rust. 0, a part of the stem magnified showing the spores protruding. D, a summer spore, which infects a new wheat plant. E, a winter spore, which infects barberry in spring. De Bary showed that in the late spring the spores from the barberry fungus are carried by the slightest puff of air to the wheat in the fields. If a spore falls on a wheat or grass stem, it puts out a little tube, and creeps along the surface of the stem until it reaches one of the pores. By this pore the tube enters the stem and then grows fast, spreading out in all directions inside the stem. After a time the xvi STOEY OF EUST IN WHEAT fungus plant is ready to form spores anew. These spores burst through the skin of the stem or leaf, and are carried by the wind to other wheat plants, which are thus infected in their turn. This goes on all through the summer weather, but autumn comes on, and the wheat plants begin to turn yellow. This is a warning to the fungus that it is time to prepare for winter. It stops producing the rust-coloured summer spores, and instead produces dark-coloured resting spores (the mildew), which have a thick coat to resist the winter cold. These dark-coloured spores remain through the winter in what is called a resting condition. When spring comes they sprout on the ground and make new spores. • But where can these go ? The wheat is very little above the ground ; it cannot yet feed a greedy fungus. But in the hedgerows the bar- berry bushes are putting out their fresh leaves. If the spores are by chance carried to these leaves, they again sprout and form pretty little yellow cups on the under side of the leaf, each cup being full of spores. These spores are carried later by the wind to the wheat, and so the whole story begins over again. This, then, is the history of rust, as it was finally worked out by de Bary. It might be said that it shows that the way to stop rust is to root 200 TILLEES OF THE GEOUND CHAP. up the barberry plants. Unfortunately, however, other botanists have shown that, though the fungus generally needs to spend part of the year on the barberry, yet in some countries, as in Australia, it seems able to do without the barberry. Even in parts of England — at least sometimes — it can do without that plant, perhaps using some other plant instead. But if we do not know yet how rust may be prevented altogether, we at least know enough now to see in what direction help is to be sought. CHAPTEE XVII PLANT FOOD AND THE UTILISATION OF THE SOIL OF all the improvements which man's toil and patience have produced in the growing of plants, perhaps in some ways the most important is the improvement of methods, especially of methods of treating the soil. It seems clear at least that, in the immediate future, the greatest progress in con- nection with agriculture will be made along the lines of the proper utilisation of the soil — in learning how to make it fertile and how to keep it so. The whole story of the way in which man has xvir UTILISATION OF THE SOIL 201 learned to use the soil aright is too long to tell here. All that we can do is to pick out a few famous names, and show with what steps in progress these names are associated. Of special importance are the questions associated with the problem of where plants get the nitrogen they require to make their proteids (see p. 117), and we shall restrict ourselves in this chapter to that problem. We will begin with the work of Baron Liebig. Liebig was a great German chemist who was born in 1803 and died in 1873. He made many great discoveries ; he invented the first meat extract ; he compounded a food for infants ; he did many other things for his country and for the world. All that we need stop to learn about him here, however, is that he was the first to state a consistent theory about the food of plants in relation to farming. This theory was called Liebig's " Mineral Theory." Theory is not perhaps the best word to apply to it, but it was the word which was used. It was not a theory in the sense of being spun from his imagination without any relation to actual fact. A scientific theory is an attempt to explain results obtained by observation and experiment. Liebig first did something. What he did was to burn many plants — to burn them under' special conditions and with great care. He burnt plants from many different localities, and 202 TILLERS OF THE GROUND .CHAP. carefully examined the results of the burning, his examination being of the kind which a chemist calls an analysis. What he found in the first place was that the results of the burning were, roughly speaking, always the same. Whether the plants grew " on the most diversified soils, in the most varied climates, whether cultivated on plains or on high mountains," the same effects were produced when they were burned. What was the effect of the burning ? In the first instance he found that the burning plant gave off a colourless gas, which stifles animals ; this gas we call carbonic acid gas. Secondly he found that it gave off small quantities of a gas called ammonia — the gas which brings the tears to our eyes when we take a big sniff of a bottle of smelling-salts. When the plant had quite burnt away, Liebig found that there was left behind a little mass, of greyish ash, like that which is left when wood burns away. In this ash he found what the chemist calls salts,^— salts of potash, lime, magnesia, and so on. Liebig said, therefore : — All plants contain carbonic acid gas, ammonia, and salts. He knew, however, that ammonia does not occur in the living plant. It is the proteid of the living plant which makes ammonia when the plant is burnt. He knew also that the carbonic acid gas produced by plants when they are burnt is got from the air ; xvn UTILISATION OF THE SOIL 203 it does not need to be supplied in manure. He believed, further, that plants could also take ammonia from the air, and use it to build up proteid. The practical conclusions which Liebig drew from his experiments, then, were that farmers need not trouble about giving their plants nitrogenous manure. The air, he said, contains plenty of nitrogen, just as it contains plenty of carbonic acid gas. Plants can get as much of these substances as they want. They cannot get salts from the air — these must be given in manure, but nitrogen need not be given. These statements of Liebig gave rise to fierce discussion and to not a little quarrelling. Farmers had always been in the habit of giving their plants some form of nitrogenous manure, and they said that they were quite certain that wheat, for instance, would not grow without such manure. Liebig, on the other hand, said that, as there was plenty of nitrogen in the air, it was a pure waste of money to give nitrogenous manures to the plants. We know now that the farmers were right, at least for most plants, and that Liebig was wrong ; but never- theless he did a great deal for scientific agriculture, though he happened to be partly wrong on the question whether plants took their nitrogen from the air or from the soil. One step of great importance which he took was 204 TILLEES OF THE GEOUND CHAP. to show farmers that when natural manure could not be got, then mineral substances could, to at least a large extent, be used in its place. He showed this practically by an experiment at which the farmers laughed a little, but which was never- theless of great importance as an experiment. He bought a little piece of almost barren ground, and by treating it with mineral manures, together with some other substance, he succeeded in getting from this barren land as good crops as his neigh- bours got from their fertile fields. The experiment was costly, for he put into his land, in the form of mineral manure, more than he got out in crops, but still it was very important to show that soil could be made fertile by adding the chemical substances which were naturally lacking in it. The fate of this plot is rather interesting. " In the year 1849," says Liebig, "my former gardener, Kappes, purchased the land from me ; and this industrious man, who has not the means to buy manure, farms with profit the little property, now in good heart. He is able, with the help of a small coffee and beer trade in the summer months, to support himself and his family on it ; he keeps two cows, raises annually several oxen, and has gained what has enabled him to increase the farm buildings, — and all this without ammonia or humus —by means of mineral manure alone." xvii UTILISATION OF THE SOIL 205 What Liebig did for Kappes, he did really for the world ; for our bread and meat to-day would be much dearer than they are were it not that Liebig had taught the farmers the value of mineral manures. Much about the same time that Liebig was working at this subject, a French agricultural chemist, called Boussingault, was also interesting himself in the chemistry of plants. In his book on Rural Economy he speaks of the difficult subject of the source of plant nitrogen, and of a series of experiments he made in connection with it. Let us quote a few words from this book, in connection with these experiments: — " I had necessarily," he says, " to follow a method of inquiry different from any which had yet been taken ; I had no chance of arriving at more definite results than those which had been already come to, had I chosen the old line of investigation. I there- fore called in the aid of elementary analysis, with a view of comparing the composition of the seed with the composition of the harvest produced from it, at the sole cost of water and the air. By pro- ceeding in this way I believed that the problem was capable of solution ; without flattering myself that I have completely resolved it, I conceive that something has been done in the right direction. The subject is one of the most delicate imaginable, and he who enters it requires indulgence." 206 TILLERS OF THE GROUND CHAP. What did Boussingault actually do? His object was to grow plants from seed, giving them nothing but water and air, and then find out if they con- tained more or less nitrogen than was in the original seed. If there was more in the little plant than in the seed from which it grew, and the plantt was given no nitrogenous manure, then it must have taken this nitrogen from the air. In other words, Boussingault wanted to answer the question : — Can a green plant take nitrogen from the air ? He made in the first place a series of very careful experiments, which seemed to show that clover and peas can take nitrogen from the air while wheat and oats cannot do this. He was not, however, satisfied with these results, for he could discover no reason why peas and clover should differ so markedly from wheat and oats. He, therefore, returned to his experiments again and again, always endeavouring to make the conditions more precise. For more than twenty years he toiled over the question, and his final conclusion was that plants cannot take free nitrogen from the air. That is, he answered his own question in the negative, believing that he had been misled in his first experiments with clover and peas. A great number of other observers worked at the same question, and with very varying results, some xvn UTILISATION OF THE SOIL 207 asserting that plants could take up nitrogen from the air, and the majority that they could not. Among the most important of the negative results were those of the experiments carried out by Sir John Lawes and Sir Joseph Gilbert. These experiments were carried out at Kotham- sted, near St. Albans in Hertfordshire, a name which should be known to every Englishman, for there have been carried out at this place experiments the value of which for English agriculture and for the world can scarcely be over-estimated. The Eothamsted experiments, carried out very carefully for a long period of time, showed that there is no evidence that the members of the Grass family have the power of taking free nitrogen from the air ; nitrogen must be given to their roots in a combined form before it is any use to them. As regards the plants of the Pea family, the experi- ments, like the later experiments of Boussingault, showed no gain of nitrogen, but — and this is an im- portant point — Lawes and Gilbert state definitely that it did not seem to them that the plants of this family grew satisfactorily during their ex- periments, and they were not satisfied that, under better conditions, these plants might not have shown that they could take up free nitrogen. This important paper was published in 1860, and it was generally supposed to "have settled the 208 TILLEES OF THE GBOUND CHAP. question — it did settle it for nearly thirty years. But even this paper ends with a doubt, for the authors say that if no plant can take free nitrogen from the air, then it is not clear how the supply of combined nitrogen in the soil is kept up. The air is full of free nitrogen, but if it is no use to plants then they must depend entirely upon the combined nitrogen of the soil. But every year our rivers are carrying out to the sea a large, amount of combined nitrogen, which has been taken from the land and is swept out to the sea where it is useless to man. Is the soil then every day growing poorer ? Will there come a day when there is no longer enough manure to grow the crops necessary to keep man alive ? Will the earth grow poorer and poorer, and the crops smaller and smaller till we come nearer and nearer starvation ? This was the problem that was left, or at least the practical side of it. Then there was also the theoretical side ; this curious mystery of pea and clover, which seemed sometimes able to fix free nitrogen, but always lost their power of doing so when they were tested under the rigid conditions of an experiment. When would the key to this mystery be found ? . Although for many years it was generally believed that no fixation of free nitrogen occurred, yet experiments' went on, many different people xvn UTILISATION OF THE SOIL 209 being interested in the subject, and following it along many different lines. One point of great importance caine out of researches which had only an indirect reference t-o the nitrogen problem. This was the gradual development of our knowledge of FIG. 45. — Camels carrying Green Berseem, or Egyptian Glover, to market in Egypt. The clover is grown both as a food for animals and because it improves the soil. the minute organisms called bacteria, which were shown to be the causes of many processes previously regarded as mysterious. In 1876 the great French chemist Berthelot pointed out the possibility that bacteria with the power of fixing free nitrogen exist in normal soil. This, as he showed, might explain some of the differences between Boussingault's various experi- p 210 TILLEKS OF THE GROUND CHAP. ments, for in some of these the sand in which the plants were grown was so treated that it could not be supposed to contain living bacteria. In the Rothamsted experiments also, the sand was carefully sterilised, that is, any bacteria present were killed before the experiment began. Berthelot made some other suggestions and performed some experiments which helped to throw light upon the problem, though they did not solve it. He died, it may be mentioned, in 1907, and was one of the last of the great scientific men of the middle of the nineteenth century. Many tales might be told of him, but for these we have no space now, no space even to tell of the dignity with which at the last he laid down his finished task, and entered into rest. That is, however, a story which is well worth reading. Going back to the nitrogen problem, we find that when Berthelot had made the suggestion about the bacteria the answer was nearly found, though it was ten more years before it was finally given. In 1886, a German man of science named Hellriegel read at a meeting in Berlin a paper on a long series of experiments which he had performed. These experiments gave the following results. Clover, peas, beans, and other plants of the Pea family have usually on the roots little nodules XVII UTILISATION OF THE SOIL 211 seed only nodules if are living which contain bacteria. These bacteria possess the power of fixing free nitrogen. Plants of the Grass family, turnips, and other food-plants not belonging to the Pea family, do not possess these nodules, and cannot fix free nitrogen. Clover or peas grown from develop the the bacteria in the soil. This is the reason why Boussingault's experi - ments andtheKothamsted experiments were so con- tradictory, for sometimes nodules were present and sometimes they were not. When they were present the plant could fix free nitrogen, when they were not it could not. A number of other investigations were made which confirmed these statements, and we know now the reason why clover enriches soils. It is not the clover which enriches the soil, but the insignificant bacteria on its roots, which can take free nitrogen from the air FIG. 46. —Nodules on the Roots of Clover. 212 TILLERS OF THE GROUND CHAP. and fix it in the soil in a form in which it can be used by other plants. We know now, therefore, that while most green plants must take their nitrogen from the soil in the form of a salt called a nitrate, plants like clover and peas live in partnership with bacteria which can take nitrogen from the air, and hand it on to the green plant, and also leave part of it stored in the soil for the plants of another season. Later investigations have taught us many new facts about the soil and the use of manures. It is clear now that we do not need to fear that the soil will grow poorer, for not only are there bacteria ready to enrich it for us, but the chemist also has shown how the nitrogen of the air may be fixed, with the help of lime, in a form which can be used by the higher plants, an artificial manure being thus produced. CHAPTER XVIII THE GAINS THAT KNOWLEDGE HAS BROUGHT BEFORE proceeding to sum up generally the gains that the slowly acquired knowledge of the ages has brought to mankind — gains in wealth, gains in security, gains in power to turn the stubborn xvni GAINS FBOM KNOWLEDGE 213 earth to his will, let us look for one moment at one other picture of human skill. If we cross the Channel to France, and travel eastwards till we reach Paris, we find that, like London, like all large cities, Paris is surrounded by a ring of market-gardens, a circle of highly cultivated land, the object of which is to supply some part, at least, of the needs of the great city. But just as the English farmer is the most skilful in the world, and gets more from his wheat land than any other, so the market-gardeners round Paris are the most skilful in the world, and can do marvels which no others can imitate with their tiny patches. The English farmer has won the favour of the goddess of fertility, who pours her golden grain into his lap in unstinted showers. It is a more stubborn goddess that the French gardeners woo. Proserpine, the goddess of spring flowers, of sprouting corn, and of unfolding leaves, comes tardily every- where, for the time seems long till she appears. But while others must wait her coming, 'be it soon or late, the gardeners of Paris can bring her at their will. So powerful a charm have they, that, in bleakest January, she will smile beneath their frames. Nay more, while elsewhere the spring, though it come with lagging feet, must neverthe- less fly at the approach of summer, here these skilful tillers of the ground can make her linger at their will. What exactly does all this mean ? Some of us have perhaps been in Paris. If not, we have perhaps heard others tell of the flowers which are to be always seen in the streets of that city. On certain special days, whatever the season, these flowers seem to be found everywhere. Flowers . in bunches, flowers growing in pots, flowers over- flowing the pavements — there is no end to them. These days when the flowers are so plentiful are nearly always Saints' days, and the reason for their abundance then is rather curious. In France, it is customary to give the children the names of some one or other of the great Saints, and then very often, instead of the birthday of the boy or girl, it is the name-day, the Saint's day, which is kept as a family festival. The French love flowers, and in Paris there are many Jeans and Jeannes, many Louis and Catherines, many Jacques and Maries. Therefore, on every one of the Saints' days, there will be many people who want to buy a pot or a bunch of sweet-smelling flowers for some relative or other. Therefore, again, the gardeners make great preparations for these days. A Paris gardener is reckoned really clever when he can make hundreds of pots of daisies or roses or UAIJNS .bKUM JUN'OWLEDU^ 215 lily of the valley, or some other beautiful flower, show a lovely mass of bloom just on the eve of a great Saint's day. If the season be an early one he must keep his plants back ; if it be a late one he must force them on. In any case he must know how to arrange things so that the flowers are neither a day too late nor a day too early, but just at their best the morning they are wanted. It would take too long to tell even some of the ways in which the gardener makes himself almost independent of the seasons. A few words we must say, however, of his methods. By centuries of striving the French gardener has reached a level which his forefathers never even dreamt of. He does not, of course, confine himself to flowers. A great many of the early delicacies of the Paris and also of the London markets are pro- duced in his gardens. Early salads, early aspar- agus, early peas, early strawberries, almost all the fruits and vegetables that come out of their season, and are therefore valuable, are grown round Paris. The two essentials of the French methods are, first, a very rich soil, and second, protection from the weather, by means of glass frames or bell glasses. The richness of the soil is produced by using enormous amounts of manure, and so clever are the L : - : - ," -' • • . -. - - _ - . - are kept. He depends upon it not only to enrich his soil, but also to heat it by the process of fermenta- tion. More and more in Paris, however, the horse is being replaced by the motor-car, and therefore FIG. 47. — A Field of Maize in Eastern Kansas. horse-manure is becoming dearer. Here is another difficulty in the way of the gardener. On the whole it seems likely that his work will get more difficult as time goes on, and that his methods will perhaps have to be changed with changing times. From what we know of the XVIII history of these gardeners in the past, however, we may be sure at least that they will learn to adapt their methods to changing conditions ; that they will not lose their control over Mother Earth. Taking the market- gar dens of Paris as a sign and a symbol of the control over Nature that knowledge has brought, let us go back and review briefly the path that lias led man so far. We began, it will be remembered, with some examples of people who made no attempt to till the ground at all, who were content with what it produced naturally. Then we came to the people who cultivated a little, but who did not know how to use the ground aright. These people seemed to be struck with the curse of Cain. We remember how it was said to him : " When thou tillest the ground it shall not henceforth yield unto thee her strength ; a fugitive and a vagabond shalt thou be in the earth." We know enough now to see that this must always be so, that unless man can succeed in making the earth yield to him of her strength, he must always be a fugitive and a vagabond, wander- ing from place to place as he exhausts the soil, incapable of making peaceful and permanent settle- ments. As contrasted with these primitive conditions, we saw that the nations which we call civilised 220 TILLEES OF THE GKOUND CHAP. have learnt step by step all the great lessons. First, the}7 found out which plants were best worth cultivating, and this — the first and greatest lesson — was learnt in three special parts of the earth's surface only. In order that these plants might be useful to all the earth, then, they had to spread out in all directions from the places where they originated, so that West might learn from East, and West again might give back a hundredfold for all that she received. As they spread, and were cultivated over larger and larger areas, the food -plants, we saw, were altered and improved, fitted for new countries and new conditions. We saw that at first the process of improvement was slow and almost un- conscious, but gradually as knowledge increased it became quicker and more certain, until now the gardener can mould his plants almost at his will. But, as man's skill increased, so also his enemies seemed to multiply. No sooner did the earth begin to bring forth abundantly than the struggle with disease and with destructive insects became fiercer, and the skill which had produced new plants, and made them more productive, had to be turned to the ways of protecting these plants against caterpillar and fungus, against beetle and fly. xvm GAINS FKOM KNOWLEDGE 221 More than this, as soon as man had learnt to till the ground, he had to learn the deeper lesson of not only making it yield of its strength, but also of making sure that there was a reserve of FIG. 48. — Cutting and binding Oats in Ontario. strength for the future. He has had to learn what his crops are taking from the land, in order to learn what he must give back to the land. He has had to learn to take advantage of the tiny bacteria on the roots of clover and peas in order that his corn crops may not fail. He has had to 222 TILLERS OF THE GROUND CHAP. learn also to take from the dreary deserts of Chile, and from the desolate, uninhabited islands of the Pacific, the substances which will bring fertility to his exhausted lands. He is learning now to utilise modern chemistry and modern electricity to make nitrogenous manures from the air itself. In tracing in this way the development of the gardener and farmer of to-day from the first tillers of the ground, we have every now and then stopped to mention certain great names, the names of the men who have stood out from among their fellows, who mark the great periods of change in thought or in methods. But even the shortened story as we have read it here shows us one fact, a fact which would have been clearer if the story had been told in full. This is that the great men are after all only the milestones which mark the fact that a certain point in the journey has been reached. The great men make progress visible, but this progress would not have been possible if it had not been for the work of the unnoticed toilers, who smoothed the path for the labour of the others. This is one of the reasons why it is well for us to know the story of the development not of one form of knowledge only, but of many — that we may learn that progress in knowledge, like progress in walking along a road, comes from a great xvm GAINS FKOM KNOWLEDGE 223 number of steps, each one insignificant in itself. The great men mark the fact that during such and such a time so much progress has been made, but the great onward sweep of knowledge has come as truly from the work of the lesser as from that of the greater men. We cannot all do great work ; we cannot hope that the work of each one of us will mark the beginning of a period, but we should not forget that the doing of small pieces of work lies within our power, and that is one of the great necessities for progress. Here is an interesting little quotation from a book by a French author, called Anatole France, on this subject. The hero of the book has been talk- ing to his little boy about the first men of Europe, who lived in caves and had only weapons of flint or of bone, and who yet had learnt many things. He ends up by saying :— " But the task is not yet finished. We should be less generous than the Men of the Caves if, now that our turn has come, we did not strive to render life better and more secure for our children than it is for ourselves. For that there are two secrets — loving and knowing. By knowledge and by love the world is made." We have seen here that what the slow develop- ment of agriculture has done has been " to render life better and more secure " for mankind, but in 224 TILLEES OF THE GEOUND CH. xvm this, as in all departments of knowledge, the task is not yet finished, and it is ours to aid it either by our work or by our sympathy with the workers. Only thus can we carry on the work which the men of the Stone Age began. THE END Printed by R. & R. CLARK, LIMITED, Edinburgh. READABLE BOOKS IN NATURAL KNOWLEDGE Illustrated. Globe Svo. is. 6d. each WONDERS OF PHYSICAL SCIENCE* By E. E. FOURNIER, B.Sc. TILLERS OF THE GROUND. By MARION I, NEWBIGIN, D.Sc. THREADS IN THE WEB OF LIFE. By Professor J. ARTHUR THOMSON, JVLA., and MARGARET R. THOMSON. THE PAST AT OUR DOORS, By WALTER W. SKEAT. And others to follow LONDON : MACMILLAN AND CO., LTD. N. 3.4.10 TILLERS OF THE GROUND BY MARION I. NEWBIGIN, D.Sc. CONTENTS Chapter i. Primitive Tillers of the Ground. 2. Reclaiming the Desert. 3. Some Contrasts. 4. The Beginnings of Agriculture. 5. The Spreading of Food-Plants. 6. The Spreading of Food-Plants (continued). 7. Overcoming Difficulties — The Date and the Fig. 8. Introducing Dates into North America; 9. The Story, of the Smyrna Fig. 10. Food and Food-Plants, n. The Chief Kinds of Food-Plants. 12. Improving Cultivated Plants. 13. Experiments in Plant-Breeding. 14. Making New Plants. 15, The Struggle with Disease. 16. The Story of Rust in Wheat. 17. Plant Food and the Utilisation of the Soil. 18. The Gains that Knowledge has brought. THREADS IN THE WEB OF LIFE BY PROFESSOR J. ARTHUR THOMSON, M.A. AND MARGARET R. THOMSON CONTENTS Chapter i. Man as Hunter. 2. Domesticated Animals. 3. Domes- ticated Animals (continued). 4. Earthworms and their Work. 5. Man's Struggle with Animals — The Flesh-eating Animals. 6. Animals which destroy Man's Crops. 7. The Balance of Nature. 8. Pasteur and his Work. 9. Mosquitoes and Malaria. 10. Inter-Relations among Animals, n. Aids in the Struggle for Existence. 12. Social Life among Animals. 13. Social Insects. 14. Inter-Relations among Plants. LONDON : MACMILLAN AND CO., LTD. A University of Toronto Library DO NOT REMOVE THE CARD FROM THIS POCKET Acme Library Card Pock. LOWE-MARTIN CO. LIMITED