Chapter 6

In some few instances it is obvious that this variability is of later date than culture. The most conspicuous case is that of the coconut. This valuable palm is found on nearly all tropical coasts, in America, as well as in Asia, but in Africa and Australia there are many hundreds of miles of shore line, where it is not found. Its importance is not at all the same everywhere. On the shores and islands of the Indian Ocean and the Malay Archipelago, man is chiefly dependent upon it, but in America it is only of subordinate usefulness.

In connection with these facts, it abounds in subspecies and varieties in the East Indian regions, but on the continent of America little attention has as yet been given to its diverging qualities. In the Malayan region it affords nearly all that is required by the inhabitants. The value of its fruit as food, and the delicious beverage which it yields, are well known. The fibrous rind is not less useful; it is manufactured into a kind of cordage, mats and floor-cloths. An excellent oil is obtained from the kernel by compression. The hard covering of the stem is converted into drums and used in the construction of huts; the lower part is so hard as to take on a beautiful polish [83] when it resembles agate. Finally the unexpanded terminal bud is a delicate article of food. Many other uses could be mentioned, but these may suffice to indicate how closely the life of the inhabitants is bound up with the culture of this palm, and how sharply, in consequence, its qualities must have been watched by early man. Any divergence from the ordinary type must have been noted; those which were injurious must have been rejected, but the useful ones must have been appreciated and propagated. In a word any degree of variability afforded by nature must have been noticed and cultivated.

More than fifty different sorts of the coconut are described from the Indian shores and islands, with distinct local and botanical names. Miquel, who was one of the best systematists of tropical plants, of the last century, described a large number of them, and since, more have been added. Nearly all useful qualities vary in a higher or lesser degree in the different varieties. The fibrous strands of the rind of the nut are developed in some forms to such a length and strength as to yield the industrial product known as the coir-fibre. Only three of them are mentioned by Miquel that have this quality, the _Cocos nucifera rutila_, _cupuliformis_ and _stupposa_. Among them the _rutila_ [84] yields the best and most supple fibres, while those of the _stupposa_ are stiff and almost unbending.

The varieties also differ greatly in size, color, shape and quality, and the trees have also peculiar characteristics. One variety exhibits leaves which are nearly entire, the divisions being only imperfectly separated, as often occurs in the very first leaves of the seedlings of other varieties. The flavor of the flesh, oil and milk likewise yield many good varietal marks.

In short, the coconut-palm comes under the general rule, that botanical species are built up of a number of sharply distinguishable types, which prove their constancy and relative independence by their wide distribution in culture. In systematic works all these forms are called varieties, and a closer investigation of their real systematic value has not yet been made. But the question as to the origin of the varieties and of the coconut itself has engrossed the attention of many botanists, among whom are De Candolle in the middle of the last century, and Cook at its close.

Both questions are closely connected. De Candolle claimed an Asiatic origin for the whole species, while Cook's studies go to prove that its original habitat is to be sought in the northern countries of South America. Numerous [85] varieties are growing in Asia and have as yet not been observed to occur in America, where the coconut is only of subordinate importance, being one of many useful plants, and not the only one relied upon by the natives for their subsistence. If therefore, De Candolle's opinion is the right one, the question as to whether the varieties are older or younger than the cultivated forms of the species, must always remain obscure. But if the proofs of an American origin should be forthcoming, the possibility, and even the probability that the varieties are of later date than the beginning of their culture, and have originated while in this condition must at once be granted. An important point in the controversy is the manner in which the coconuts were disseminated from shore to shore, from island to island. De Candolle, Darwin and most of the European writers claim that the dispersal was by natural agencies, such as ocean-currents. They point out that the fibrous rind or husk would keep the fruits afloat, and uninjured, for many days or even many weeks, while being carried from one country to another in a manner that would explain their geographic distribution. But the probability of the nuts being thrown upon the strand, and far enough from the shore to find suitable conditions for their germination, is a very small one. To insure [86] healthy and vigorous seedlings the nuts must be fully ripe, after which planting cannot be safely delayed for more than a few weeks. If kept too moist the nuts rot. If once on the shore, and allowed to lie in the sun, they become overheated and are thereby destroyed; if thrown in the shade of other shrubs and trees, the seedlings do not find the required conditions for a vigorous growth.

Some authors have taken the fibrous rind to be especially adapted to transport by sea, but if this were so, this would argue that water is the normal or at least the very frequent medium of dissemination, which of course it is not. We may, claim with quite as much right that the thick husk is necessary to enable the heavy fruit to drop from tall trees with safety. But even for this purpose the protection is not sufficient, as the nuts often suffer from falling to such a degree as to be badly injured as to their germinating qualities. It is well known that nuts, which are destined for propagation, are as a rule not allowed to fall off, but are taken from the trees with great care.

Summing up his arguments, Cook concludes that there is little in the way of known facts to support the poetic theory of the coconut palm dropping its fruits into the sea to float away to barren islands and prepare them for [87] human habitation. Shipwrecks might furnish a successful method of launching viable coconuts, and such have no doubt sometimes contributed to their distribution. But this assumption implies a dissemination of the nuts by man, and if this principal fact is granted, it is far more natural to believe in a conscious intelligent dissemination.

The coconut is a cultivated tree. It may be met with in some spots distant from human dwellings, but whenever such cases have been subjected to a closer scrutiny, it appears that evidently, or at least probably, huts had formerly existed in their neighborhood, but having been destroyed by some accident, had left the palm trees uninjured. Even in South America, where it may be found in forests at great distances from the sea-shore, it is not at all certain that true native localities occur, and it seems to be quite lost in its natural condition.

Granting the cultivated state of the palms as the only really important one, and considering the impossibility or at least great improbability of its dissemination by natural means, the distribution by man himself, according to his wants, assumes the rank of an hypothesis fully adequate to the explanation of all the facts concerning the life-history of the tree.

We now have to inquire into the main question, [88] whether it is probable that the coconut is of American or of Asiatic origin, leaving aside the historic evidence which goes to prove that nothing is known about the period in which its dissemination from one hemisphere to another took place, we will now consider only the botanic and geographic evidence, brought forward by Cook. He states that the whole family of coconut-palms, consisting of about 20 genera and 200 species, are all strictly American with the exception of the rather aberrant African oilpalm, which has, however, an American relative referred to the same genus. The coconut is the sole representative of this group which is connected with Asia and the Malayan region, but there is no manifest reason why other members of the same group could not have established themselves there, and maintained an existence under conditions, which are not at all unfavorable to them. The only obvious reason is the assumption already made, that the distribution was brought about by man, and thus only affected the species, chosen by him for cultivation. That the coconut cannot have been imported from Asia into America seems to be the most obvious conclusion from the arguments given. It should be briefly noted, that it was known and widely distributed in tropical America at the time of the discovery of that continent [89] by Columbus, according to accounts of Oviedo and other contemporary Spanish writers.

Concluding we may state that according to the whole evidence as it has been discussed by De Candolle and especially by Cook, the coconut-palm is of American origin and has been distributed as a cultivated tree by man through the whole of its wide range. This must have happened in a prehistoric era, thus affording time enough for the subsequent development of the fifty and more known varieties. But the possibility that at least some of them have originated before culture and have been deliberately chosen by man for distribution, of course remains unsettled.

Coconuts are not very well adapted for natural dispersal on land, and this would rather induce us to suppose an origin within the period of cultivation for the whole group. There are a large number of cultivated varieties of different species which by some peculiarity do not seem adapted for the conditions of life in the wild state. These last have often been used to prove the origin of varietal forms during culture. One of the oldest instances is the variety or rather subspecies of the opium-poppy, which lacks the ability to burst open its capsules. The seeds, which are thrown out by the wind, in the common forms, through the apertures underneath [90] the stigma, remain enclosed. This is manifestly a very useful adaptation for a cultivated plant, as by this means no seeds are lost. It would be quite a disadvantage for a wild species, and is therefore claimed to have been connected from the beginning with the cultivated form.

The large kernels of corn and grain, of beans and peas, and even of the lupines were considered by Darwin and others to be unable to cope with natural conditions of life. Many valuable fruits are quite sterile, or produce extremely few seeds. This is notoriously the case with some of the best pears and grapes, with the pine-apples, bananas, bread-fruits, pomegranate and some members of the orange tribe. It is open to discussion as to what may be the immediate cause of this sterility, but it is quite evident, that all such sterile varieties must have originated in a cultivated condition. Otherwise they would surely have been lost.

In horticulture and agriculture the fact that new varieties arise from time to time is beyond all doubt, and it is not this question with which we are now concerned. Our arguments were only intended to prove that cultivated species, as a rule, are derived from wild species, which obey the laws discussed in a previous lecture. The botanic units are compound entities, and [91] the real systematic units in elementary species play the same part as in ordinary wild species. The inference that the origin of the cultivated plants is multiple, in most cases, and that more than one, often many separate elementary forms of the same species must originally have been taken into cultivation, throws much light upon many highly important problems of cultivation and selection. This aspect of the question will therefore be the subject of the next lecture.

[92]

LECTURE IV

SELECTION OF ELEMENTARY SPECIES

The improvement of cultivated plants must obviously begin with already existing forms. This is true of old cultivated sorts as well as for recent introductions. In either case the starting-point is as important as the improvement, or rather the results depend in a far higher degree on the adequate choice of the initial material than on the methodical and careful treatment of the chosen varieties. This however, has not always been appreciated as it deserves, nor is its importance at present universally recognized. The method of selecting plants for the improvement of the race was discovered by Louis Vilmorin about the middle of the last century. Before his time selection was applied to domestic animals, but Vilmorin was the first to apply this principle to plants. As is well known, he used this method to increase the amount of sugar in beets and thus to raise their value as forage-crops, with such success, that his plants have since been used for the production [93] of sugar. He must have made some choice among the numerous available sorts of beets, or chance must have placed in his hands one of the most appropriate forms. On this point however, no evidence is at hand.

Since the work of Vilmorin the selection-principle has increased enormously in importance, for practical purposes as well as for the theoretical aspect of the subject. It is now being applied on a large scale to nearly all ornamental plants. It is the one great principle now in universal practice as well as one of preeminent scientific value. Of course, the main arguments of the evolution theory rest upon morphologic, systematic, geographic and paleontologic evidence. But the question as to how we can coordinate the relation between existing species and their supposed ancestors is of course one of a physiologic nature. Direct observation or experiments were not available for Darwin and so he found himself constrained to make use of the experience of breeders. This he did on a broad scale, and with such success that it was precisely this side of his arguments that played the major part in convincing his contemporaries.

The work of the breeders previous to Darwin's time had not been very critically performed. Recent analyses of the evidence obtained [94] from them show that numerous types of variability were usually thrown together. What type in each case afforded the material, which the breeder in reality made use of, has only been inquired into in the last few decades. Among those who have opened the way for thorough and more scientific treatment are to be mentioned Rimpau and Von Rumker of Germany and W.M. Hays of America.

Von Rumker is to be considered as the first writer, who sharply distinguished between two phases of methodical breeding-selection. One side he calls the production of new forms, the other the improvement of the breed. He dealt with both methods extensively. New forms are considered as spontaneous variations occurring or originating without human aid. They have only to be selected and isolated, and their progeny at once yields a constant and pure race. This race retains its character as long as it is protected against the admixture of other minor varieties, either by cross-pollination, or by accidental seeds.

Improvement, on the other hand, is the work of man. New varieties of course can only be isolated if chance offers them; the improvement is not incumbent on chance. It does not create really anything new, but develops characters, which were already existing. It brings [95] the race above its average, and must guard constantly against the regression towards this average which usually takes place.

Hays has repeatedly insisted upon the principle of the choice of the most favorable varieties as the foundation for all experiments in improving races. He asserts that half the battle is won by choosing the variety which is to serve as a foundation stock, while the other half depends upon the selection of parent-plants within the chosen variety. Thus the choice of the variety is the first principle to be applied in every single case; the so-called artificial selection takes only a secondary place. Calling all minor units within the botanic species by the common name of varieties, without regard to the distinction between elementary species and retrograde varieties, the principle is designated by the term of "variety-testing." This testing of varieties is now, as is universally known, one of the most important lines of work of the agricultural experiment stations. Every state and every region, in some instances even the larger farms, require a separate variety of corn, or wheat, or other crops. They must be segregated from among the hundreds of generally cultivated forms, within each single botanic species. Once found, the type may be ameliorated according to the local conditions [96] and needs, and this is a question of improvement.

The fact that our cultivated plants are commonly mixtures of different sorts, has not always been known. The first to recognize it seems to have been the Spanish professor of botany, Mariano Lagasca, who published a number of Spanish papers dealing with useful plants and botanical subjects between 1810 and 1830, among them a catalogue of plants cultivated in the Madrid Botanical Garden. Once when he was on a visit to Colonel Le Couteur on his farm in Jersey, one of the Channel Islands off the coast of France, in discussing the value of the fields of wheat, he pointed out to his host, that they were not really pure and uniform, as was thought at that time, and suggested the idea that some of the constituents might form a larger part in the harvest than others. In a single field he succeeded in distinguishing no less than 23 varieties, all growing together. Colonel Le Couteur took the hint, and saved the seeds of a single plant of each supposed variety separately. These he cultivated and multiplied till he got large lots of each and could compare their value. From among them he then chose the variety producing the greatest amount of the finest, whitest and most nutritious flour. This he eventually placed in the [97] market under the name of "Talavera de Bellevue." It is a tall, white variety, with long and slender white heads, almost without awns, and with fine white pointed kernels. It was introduced into commerce about 1830, and is still one of the most generally cultivated French wheats. It was highly prized in the magnificent collection of drawings and descriptions of wheats, published by Vilmorin under the title "Les meilleurs bles" and is said to have quite a number of valuable qualities, branching freely and producing an abundance of good grain and straw. It is however, sensitive to cold winters in some degree and thereby limited in its distribution. Hallett, the celebrated English wheat-breeder, tried in vain to improve the peculiar qualities of this valuable production of Le Couteur's.

Le Couteur worked during many years along this line, long before the time when Vilmorin conceived the idea of improvement by race selections, and he used only the simple principle of distinguishing and isolating the members of his different fields. Later he published his results in a work on the varieties, peculiarities and classification of wheat (1843), which though now very rare, has been the basis and origin of the principle of variety-testing.

The discovery of Lagasca and Le Couteur was [98] of course not applicable to the wheat of Jersey alone. The common cultivated sorts of wheat and other grains were mixtures then as they are even now. Improved varieties are, or at least should be, in most cases pure and uniform, but ordinary sorts, as a rule, are mixtures. Wheat, barley and oats are self-fertile and do not mix in the field through cross-pollination. Every member of the assemblage propagates itself, and is only checked by its own greater or less adaptation to the given conditions of life. Rimpau has dealt at large with the phenomenon as it occurs in the northern and middle parts of Germany. Even Rivett's "Bearded wheat," which was introduced from England as a fine improved variety, and has become widely distributed throughout Germany, cannot keep itself pure. It is found mingled almost anywhere with the old local varieties, which it was destined to supplant. Any lot of seed exhibits such impurities, as I have had the opportunity of observing myself in sowings in the experimental-garden. But the impurities are only mixtures, and all the plants of Rivett's "Bearded wheat," which of course constitute the large majority, are of pure blood. This may be confirmed when the seeds are collected and sown separately in cultures that can be carefully guarded.

[99] In order to get a closer insight into the causes of this confused condition of ordinary races, Rimpau made some observations on Rivett's wheat. He found that it suffers from frost during winter more than the local German varieties, and that from various causes, alien seeds may accidentally, and not rarely, become mixed with it. The threshing-machines are not always as clean as they should be and may be the cause of an accidental mixture. The manure comes from stables, where straw and the dust from many varieties are thrown together, and consequently living kernels may become mixed with the dung. Such stray grains will easily germinate in the fields, where they find more congenial conditions than does the improved variety. If winter arrives and kills quantities of this latter, the accidental local races will find ample space to develop. Once started, they will be able to multiply so rapidly, that in one or two following generations they will constitute a very considerable portion of the whole harvest. In this way the awnless German wheat often prevails over the introduced English variety, if the latter is not kept pure by continuous selection.

The Swiss wheat-breeder Risler made an experiment which goes to prove the certainty of the explanation given by Rimpau. He observed on his farm at Saleves near the lake of Geneva that after a lapse of time the "Galland wheat" deteriorated and assumed, as was generally believed, the characters of the local sorts. In order to ascertain the real cause of this apparent change, he sowed in alternate rows in a field, the "Galland" and one of the local varieties. The "Galland" is a race with obvious characters and was easily distinguished from the other at the time when the heads were ripe. They are bearded when flowering, but afterwards throw off the awns. The kernels are very large and yield an extraordinarily good, white flour.

During the first summer all the heads of the "Galland" rows had the deciduous awns but the following year these were only seen on half of the plants, the remainder having smooth heads, and the third year the "Galland" had nearly disappeared, being supplanted by the competing local race. The cause of this rapid change was found to be twofold. First the "Galland," as an improved variety, suffers from the winter in a far higher degree than the native Swiss sorts, and secondly it ripens its kernels one or two weeks later. At the time of harvest it may not have become fully ripe, while the varieties mixed with it had reached maturity. The wild oat, _Avena fatua_, is very common in [101] Europe from whence it has been introduced in the United States. In summers which are unfavorable to the development of the cultivated oats it may be observed to multiply with an almost incredible rapidity. It does not contribute to the harvest, and is quite useless. If no selection were made, or if selection were discontinued, it would readily supplant the cultivated varieties.