CHAPTER II

HARMONIES AND DISHARMONIES AMONGST BEINGS INFERIOR TO MAN

The organised world before the appearance of man on the earth—Absence of a law of universal progress—Fertilisation of vanilla—The part played by insects in the fertilisation of orchids—Mechanism by which insects carry the pollen of orchids—Habits of fossorial wasps—Harmonies in nature—Useless organs—Rudiments of the pollinia of orchids—Disharmonies in nature—Unadapted insects—Aberration of instincts—Perversion of sexual instinct—Attraction of insects by light—Luminous insects—Law of natural selection—Happiness and unhappiness in the organised world

Long before man appeared on the earth animals and plants were distributed over it. Some of these were endowed with but vague senses, while others had well-developed instincts, and some even a certain degree of intelligence which they applied for their self-preservation and for the propagation of their own kind.

Many species, well adapted for the resistance of external influences, have survived from very early times to the present day. In the Carboniferous period birds and mammals did not yet exist, and the thick forests, with undergrowths of gigantic ferns, were inhabited by large numbers of articulated animals, amongst which were scorpions and insects. The scorpions of that time resemble in every way those that actually live at the present day in tropical countries; and amongst the insects of that early epoch were some very like the cockroaches of to-day. Certain tree-like ferns of the present time are also very similar to those of the coal period. Amongst the animals the bodies of which are protected by a shell, such as foraminifera and mollusca, certain species have survived even from an earlier time than the coal period.

In contrast with this extraordinary survival, there are instances of the complete disappearance of numbers of species of animals and plants. In early times, during the Tertiary epoch, the virgin forests of Europe were inhabited by a large number of monkeys, of which fossil remains are now found, especially in Greece. These formerly existed even in Europe, and some anthropoid apes (_Dryopithecus_) have left traces in the tertiary deposits of France.[28] These animals, notwithstanding that their organisation was superior to that of scorpions and cockroaches, have not been able to adapt themselves to the altered conditions of modern Europe. A similar fate has come upon some of the higher mammals, such as the mammoth and the mastodon.

These facts do not bear testimony to the prevalent idea that there exists in nature a law of universal progress tending to the production of organisms more and more perfect from the point of view of complexity of structure. It is incontestable that forms higher in the scale of life have developed only after the appearance of lower forms. But it does not follow that development always takes a progressive march. Man is one of the later species that have appeared upon the earth, but there are others of still more recent date. It is very probable that certain species of lice have appeared subsequent to man, particularly the clothes-louse (_Pediculus vestimenti_). Amongst the true parasites which live only in the human body are some that have acquired their specific characters after the appearance of man. Such are certain tape-worms and microbes, such as a species of _gonococcus_. It is therefore amongst parasites and not to man that we must look for the latest products of creation.

In nature, then, there is no blind tendency towards progress. Organisms almost innumerable are born every day with variable characters. Those amongst them which are adapted to existing circumstances survive and produce offspring like themselves, but many do not reach maturity, and, living only for a short time, die without leaving issue.

To give the reader a better idea of adaptations and of their importance to living creatures, it will, perhaps, be as well to devote some space to an account of examples of them. Amongst organisms that attract our attention by their pleasing aspect, there are not many that can rival flowering plants. Every one admires the great beauty of the blossom of orchids. There can be no doubt that these flowers have not been developed to satisfy the æsthetic tastes of man, for the simple reason that orchids existed for a long time before man’s appearance.

Among orchids there is one which, for more than half a century, has been cultivated by man in many tropical countries. This is the Vanilla, the fruit of which produces one of the sweetest of spices.

In former days the pods of only the wild vanilla, which is an undergrowth of the forests of Mexico and South America, were gathered. But the employment of vanilla to flavour chocolate has rendered its artificial culture lucrative; consequently the plant has been transported to several warm countries where it could be acclimatised. It has flourished and borne numerous blossoms, but it has never produced fruit from which alone the aroma is obtained. As the question of the sterility of the vanilla was of great practical interest to the cultivator, the matter was investigated, and it was found that the flower remained sterile because the female and male parts could not come in contact. The pistils and stamens of the flower are well developed, but between these sexual organs is a membrane which prevents fertilisation. After this discovery was made, the idea occurred that the pollen of the vanilla flower might be transferred artificially to the stigma of the pistil so as to bring about “artificial” fertilisation. A young black slave, Edmond Albius, a native of Réunion, discovered in 1841 a practical method by which the male and female elements of the vanilla could be put in contact; and from this discovery there came a great extension of the cultivation of the orchid in many countries. At a certain period a small bamboo point or the tooth of a comb is introduced into the vanilla flower, and in this way, in a short time, a quantity of flowers may be fertilised and so made capable of bearing mature pods.[29]

In the original home of the vanilla the intervention of man is unnecessary. In Guiana and Mexico fertilisation of the flower is the work of small bees (of the genus _Melipona_). They frequent the vanilla flowers to extract nectar, the material of their honey. Small humming-birds also hover over the vanilla blossoms, and by introducing their bills into the sexual organs of the flowers bring about contact of the male and female elements.

Sterility of the vanilla in the countries to which it has been introduced, before the employment of artificial fecundation, is easily explained by the fact that in these countries there are no insects nor humming-birds capable of transporting the pollen.

But it is not only the vanilla that requires the co-operation of living beings to produce its fruits. It is the case with many other orchids. In the flowers of these the pollen is massed together and cannot be transported by the air. It needs the aid of insects, as had already been pointed out by Sprengell in the eighteenth century, and above all by Darwin, whose splendid investigations are the basis of the following passages.[30]

Insects, belonging to different groups, such as bees, wasps, flies, certain beetles, and many butterflies and moths, visit orchids to sip the nectar produced by the plants and stored in definite parts of the flowers. In order that their proboscis may reach the stores of sweet juice, the insects inevitably touch first the upper parts of the flowers, where the anthers are present. The pollen grains are clustered in masses, known as pollinia, and these adhere to the body of the visiting insect by means of an adhesive fluid which is secreted by an organ of the flower known as the _rostellum_. In this way the pollinia adhere firmly, it may be to the proboscis of butterflies, or to the head or any other part of the body of insects. They can leave the flower and fly away without losing the adhering pollinia, and in this manner they serve as the agents for sexual contact and for fertilisation of the orchids. Ménière relates that a person who kept bees near the garden of the Faculté de Toulouse complained that they returned from the garden with their heads covered with tiny yellow bodies which he was unable to clean off from them. It was easy to recognise in these bodies the pollinia of orchids very firmly attached to the bees’ heads.[31]

When an insect, bearing these pollinia, introduces itself into another flower of the same species of orchid, it inevitably comes in contact with the female apparatus, more particularly with the viscous surface of the stigma. Some of the grains of pollen contained in the pollen-mass adhere to the stigma and are thus enabled to fertilise the ovule. This carriage of pollen from one flower to another brings about a crossing which is necessary for the production of good seed. On the other hand, the seed which is the result of self-fertilisation of a flower is inferior.

An examination of the structure and form of the flowers of many orchids show that they are adapted in a truly marvellous way to the visits of insects that convey pollen. In each part of these flowers one can discern some useful arrangement to secure cross-fertilisation.

For the proper transmission of pollen it is necessary that the pollinia should adhere very firmly to the body of the insects, and that the viscous substance which holds them together should have time to solidify. It is thus of great advantage to the plant if the insects remain for a considerable time on the flower. In several orchids the nectar is not easily accessible, and frequently the insect has to search for a long time before finding what it desires, and sometimes it even has to pierce a membranous covering before reaching the fluid. The operation takes a certain time, and this is long enough to allow the mucus by which the pollinia adhere to the insect to set firmly.

In the case of orchids the mucus of which sets instantaneously, there is no reason for the visit of the insect to be prolonged. In such cases the nectar is easy to extract, and the insect finds it without loss of time.

Darwin, after describing these facts, proceeds to say:[32]

“In these five species” (in which the viscid matter “is so adhesive that it serves to attach the pollinia firmly to the insects without getting hard”), “and in these alone, we find copious nectar ready stored for rapid suction in open nectaries. On the other hand, whenever the viscid matter gets hard by exposure for a short time to the air, it would manifestly be advantageous to the plant if insects were delayed in obtaining the nectar; and in all such species the nectar is lodged within intercellular spaces, so that it can be obtained only by the inner membrane being penetrated at several points, and this will require time. If this double relation is accidental, it is a fortunate accident for the plants; but I cannot believe it to be so, and it appears to me one of the most wonderful cases of adaptation which has ever been recorded.”

Some orchids secrete instead of nectar a clear liquid like water. This fluid is collected in a petal inserted at the lower part of the flower and shaped into a deep cup-shaped receptacle. It does not attract insects, but by wetting their wings compels them to leave the flower by a different exit which passes close to the reproductive organs (_i.e._, the anther and the stigma). The soft linings of the cup are greedily devoured by certain insects, particularly by bees. Dr. Cruger, who observed this, has often seen bees fall into the cup whereupon their wings became so wet as to prevent their flying away, and they have been obliged to get out by the channel that carries off the waste from the reservoir. As the saturated bees creep along the narrow passage after their involuntary immersion, they come inevitably in contact with the stigma and the masses of pollen. The latter adhere to the bodies of the bees and can be conveyed to the sticky stigma of a neighbouring flower.

[Illustration:

FIG. 1.—_Catasetum saccatum_ (from “La Lindenia,” Gand, 1890). ]

In other orchids (_Catasetum_, Fig. 1), the male elements are discharged by a spring-like arrangement on the body of insects. When certain parts of the flowers are touched, the pollinia are thrown off like arrows, which, in the place of the barbs, have viscid swellings. “The insect, disturbed by so sharp a blow, or after having eaten its fill, flies sooner or later away to a female plant and, whilst standing in the same position as before, the pollen-bearing end of the arrow is inserted into the stigmatic cavity, and a mass of pollen is left on its viscid surface.”[33]

After giving detailed descriptions of the cross-fertilisation of flowers by such peculiar means, Darwin makes the following remark: “Who would have been bold enough to have surmised that the propagation of a species depended on so complex, so apparently artificial, and yet so admirable an arrangement?”[34]

One orchid (_Herminium monorchis_, Fig. 2), which bears very small flowers, is remarkable for the way in which it is fertilised by insects. Only very small insects are able to penetrate the flowers. The space being very limited these minute insects can enter the flower only in a particular way, and at one of the corners. This causes the pollinia to become attached always to the same place, which is on the outer side of one of the two front legs. When the insect, the carrier of the pollinia, enters a second flower, it can scarcely fail to fertilise the stigma, which is on the corresponding side. Darwin said that it would be difficult to find a case in which there was so marvellously complete an adaptation to a very peculiar mode of fertilisation as the little flower of _Herminium_.

[Illustration:

FIG. 2.—_Herminium monorchis_

(after Sowerby, “English Botany,” ix. 1869) ]

In addition to orchids, there are other flowers the organisation of which is adapted in a remarkable way to fertilisation by insects. But to find perfect harmony in the nature of living beings it is not necessary to confine our observations to flowers. The animal world furnishes us with numerous examples. To avoid going into the details of these, I shall content myself with a description of the most remarkable instances.

Every one has seen, flying near the ground, small, slender, and pretty wasps. From time to time these bury themselves in the earth or sand, and re-appear in a few minutes. These are the fossorial wasps, the interesting habits of which have been studied by Mr. J. H. Fabre, of Avignon. They are not gregarious, but lead solitary lives and differ in their habits from their congeners. Bees feed their larvæ with honey and pollen which they take to them during the whole period of their development. Wasps are carnivorous, predatory insects, and bring their spoils to their brood of soft and feeble larvæ which are unable to provide for themselves. Bees and most wasps look after the welfare of their young ones in the fashion of human parents in nurseries.

Fossorial wasps act differently; they never see their young. They lay their eggs in burrows, sunk in the soil and hermetically sealed. The larvæ are hatched underground and are never seen by the mother. Provision sufficient for their development, however, is made in advance. Before depositing eggs, the females sink the burrows, and fill them with the spoils of the chase, which consist sometimes of spiders and sometimes of crickets or other insects. Each species of fossorial wasps preys on a particular kind of insect or on its allies, for the purpose of provisioning the burrows. These wasps are most fastidious in the choice of their food, and behave like collectors whose interest is only in a single or a few species of small animals. Léon Dufour, the well-known entomologist, was much struck by the ability displayed by certain wasps (_Cerceris_, Fig. 3) in seeking out and capturing the pretty beetles of the genus _Buprestis_, which he had great difficulty in finding himself. In making a study of these beetles he collected the material from the burrows of _Cerceris_, and so avoided the laborious task of obtaining them in the natural state of freedom. The burrows were filled with motionless, but perfectly well preserved, _Buprestes_. Although dead Coleoptera dried up in a short time, those recovered from the burrows remained in a good state of preservation for weeks. Léon Dufour came to the conclusion that the _Cerceris_ kill their prey, but inject into them some antiseptic liquid which perfectly preserves their flesh and intestines.

[Illustration:

FIG. 3.—_Cerceris_ (after Buffon). ]

J. H. Fabre pursued the study of the habits of fossorial wasps further. He ascertained that the captured insects were not dead, but only paralysed. The continuance of the function of certain organs demonstrated that the _Buprestes_, the weevils and other small creatures collected in the burrows of fossorial wasps, were alive. They could even perform some slight movements, but they were incapable of locomotion, and so could not escape. The mechanism of this paralysis, as far as could be ascertained by Fabre, is one of the most remarkable phenomena in nature. The fossorial wasps, guided by their instinct, immediately after having seized an insect or spider, bury their sting in the nervous centre which controls the movements of the legs. When animals with soft bodies, such as spiders and young crickets, are attacked, the operation does not present any difficulties. But Coleoptera in general, and the _Buprestes_ and weevils in particular, are furnished with a very hard covering which cannot be perforated by the small and slender sting of a fossorial wasp. To gain their object the wasps probe exactly between the first and second pair of legs in the median line of the under surface of the thorax. The skin is thinner at this spot, and they introduce their sting into the ganglia from which arise the nerves of the legs. In the case with the _Buprestes_ these ganglia are set close to one another, and a single prick suffices to affect the nervous centres of three pairs of legs. Once the sting has been inserted in this way the _Buprestis_ becomes paralysed, but lives for many days. “The _Cerceris_ which preys on Coleoptera,” writes Fabre,[35] “appears to have made its choice according to the dictates of an exact physiology and anatomy. It is impossible to see in its proceedings the results of happy chance; more than chance is required to explain adaptations so precise.”

After having filled the burrow with a sufficient quantity of insects or spiders, fossorial wasps lay their eggs and carefully close up the entrance. In due course the larva is hatched, and devours the food that it finds close at hand. If the gathered insects were not paralysed, they could easily escape from their prison; if they were dead, putrefaction or desiccation (according to circumstances) would render them unfit for the larvæ. It is therefore sheer necessity that is the factor in the development of this marvellous instinct that induces the fossorial wasps to attack the nervous centres of their prey. When one insect has been devoured, the larva proceeds to another, and so on, until it is fully grown, whereupon it envelops itself in a case that protects it during the winter and following spring. In summer it changes at first into a chrysalis, and later into a perfect insect. It frees itself from the cocoon, takes to flight, and enters upon life like that of its mother, which it has never seen.

Of the harmonious phenomena in nature it is indeed difficult to find other examples so perfect as those of the habits of these fossorial wasps, or of the mechanism for the fertilisation of orchids. These harmonies in nature are constantly met with in the world of living beings, and it is not astonishing that they have for a long time attracted the attention of many observers and philosophers. As it seemed impossible to attribute them to the organisms themselves, because of the low rank and lack of intelligence of these, it has seemed only natural to set them down as a manifestation of a superior force which organises and directs all natural phenomena. This argument, however, omits one side of the medal.

Any close investigation of organisation and life reveals that, beside many most perfect harmonies, there are facts which prove the existence of incomplete harmony or even absolute disharmony. The examination of the flowers of orchids would lead one to the belief that each part, even the smallest and apparently most insignificant, has its _rôle_ in the mechanism for fertilisation and cross-fertilisation. In reality it is not so. There are in certain orchids organs which do not fulfil any function.

Even among the species of _Catasetum_, in which the pollinia are thrown with force on the bodies of insects, there are some female flowers in which the male organs are rudimentary and without utility. In these flowers, according to Darwin,[36] “the two membranous sacks containing the rudimentary pollen-masses never open, but they easily separate from each other and from the anther. The tissue of which they are formed is thick and pulpy. Like most rudimentary parts, the pollen-masses vary much in size and form; they are only about one-tenth of the bulk of those of the male.” There are then, without doubt, some structures that are of no service.

The existence of these rudimentary pollinia, incapable of being transported or of fertilising the female element, is easily explained by the supposition that formerly the flowers of the _Catasetum_ were true hermaphrodites, but that in the course of time the male organs have become incompletely atrophied in certain flowers, in which, on the other hand, the female part has increased. The occurrence of an actual degeneration is shown by the existence of rudiments of the pollinia too insignificant to accomplish their normal functions.

Rudimentary and useless organs are widely distributed, and we find them in many places. Familiar instances are the atrophied eyes of animals that live in the dark, and the sometimes rudimentary sexual organs of many plants and animals.

Not only are orchids and other flowers adapted to fertilisation by means of insects, but many insects display special adaptations to their habit of visiting flowers. Butterflies, bees, and many other insects, possess mouth organs modified for the purpose of penetrating flowers to secure nectar or pollen. Other insects, again, are not so fortunate in this respect. Darwin[37] on one occasion “found an extremely minute Hymenopterous insect vainly struggling to escape, with its head cemented by the hardened viscid matter to the crest of the rostellum and to the tips of the pollinia (of an orchid, _Listera ovata_, Fig. 4). The insect was not so large as one of the pollinia, and after causing the explosion had not strength enough to remove them; it was punished for attempting a work beyond its strength, and perished miserably.”

[Illustration:

FIG. 4.—_Listera ovata_ (after Barla, “Flora of Nice,” 1868). ]

Many insects, well adapted for the purpose, delight themselves by sucking the nectar of flowers. Many others would wish to do the same, but their want of adaptation baffles them. A small “lady-bird” loves the sweet juice of flowers; it tries often to suck the nectar of the dandelion, but without success. Hermann Müller[38] has described the behaviour of this insect in procuring the nectar of _Erodium cicutorium_. “The awkward way in which this beetle, unadapted to feed on the plants, endeavours to obtain the honey, is too ludicrous not to be mentioned. After taking up a position on the petal, it puts its mouth in the direction of one of the honeycups which are situated on both sides of the base of the petal. The petal soon breaks off, upon which the insect fixes itself on a neighbouring sepal or falls to the ground with the petal. In the first case it proceeds to creep over the flower and ends by detaching all the petals; in the other case, on recovering from the shock, it quickly ascends another stem of the same plant and begins again. I have seen the same lady-bird fall four times in succession with petals which it had detached without gaining wisdom.”

The instincts of insects, well developed for certain functions, often present aberrations more or less whimsical and remarkable. The caterpillars of some butterflies, before changing into chrysalids, envelop themselves in a wellwoven cocoon capable of protecting them from noxious influences. Protected by this covering, the caterpillar changes into a chrysalid, and later into a butterfly, which perforates the end of the cocoon in order to emerge. When any external agency destroys the cocoon, normal metamorphosis becomes impossible, and the larva dies before its maturity. Fabre[39] questioned whether the caterpillar during the time of the weaving of the cocoon was capable of repairing it if it was damaged. For this object he cut with a pair of scissors the end of a cocoon in the course of construction by the caterpillar of the beautiful peacock-butterfly. In spite of the hole thus produced, the caterpillar continued its ordinary work without suspicion that it would be of no avail. On this occasion “the caterpillar of the peacock-butterfly, notwithstanding the certain fate of the future butterfly, continued peaceably to spin, without in the least modifying the regular progress of its labour; when the time had arrived for the putting in of the last defensive stitches it placed them in the perilous breach, but neglected to mend the destroyed part of the barricade. It performed its vain task, ignoring what was indispensable for success.”

Even amongst fossorial wasps, the instincts of which are so admirably developed, harmony is far from perfect. Fabre endeavoured to ascertain what effect was produced on these insects by taking away the egg laid in the burrow. He chose for this experiment the fossorial wasp _Pelopæus_ (Fig. 5), which preys on spiders. He took away the egg which had been deposited in a carefully-prepared burrow, and watched the subsequent manœuvres. “The _Pelopæus_ continued to store up spiders for the stolen egg; it gathered provisions that were not to be eaten; it redoubled its efforts to replenish a larder that I was constantly robbing with my forceps.” The insect neither discontinued its fruitless task nor appeared to be aware of its fruitlessness. Here, then, is an example of a foiled maternal instinct that gained no useful end.

[Illustration:

FIG. 5.—_Pelopæus_ (after Buffon). ]

In connection with such a slaughter for the benefit of a progeny that will never exist, I may mention observations relating to a quite different order of phenomena. There are many creatures that kill and devour their progeny. Not infrequently rabbits kill and devour all their progeny, or leave them to die without food or care. Sometimes the culprits are young rabbits without experience; but this aberration of instinct is also met with in old rabbits, which once and for all have contracted the habit of abandoning or eating their young. Some females of other species of mammals and of birds have often been surprised in the act of deserting or of killing their offspring.

Perversion of sexual instinct is frequent enough amongst animals. Huber[40] states that when male ants have a lack of females they ravish the workers, the attacks being fatal, as the sexual organs are incompletely developed and functionally incapable. Abnormal pairing has also been observed in the stag-beetle of the genus _Lucanus_, in bees, and, above all, in cockchafers.[41] Higher animals, such as dogs, furnish analogous examples of sexual perversion.

Onanism is well known amongst mammals. It is frequent among monkeys in menageries, and also in rutting stags, the latter discharging the seminal fluid by friction with trees. Stallions and mares have often been observed in the act of satisfying their sexual appetites by abnormal means. There are several other species (dogs, bears, chamois, elephants, parrakeets, etc.,) which resort to onanism.[42]

These disharmonious instincts do not in the least cause the death of the animals that manifest them. But there exist in nature instinctive aberrations much more dangerous. Who has not seen in the summer numerous insects gathered round lamps and candles, attracted by the light? Among these are Coleoptera, Neuroptera (_Phryganea_), Ephemera, and, most frequently of all, small nocturnal Lepidoptera. After flying round and round the light several times, they singe their wings and die in numbers. This instinct is so constant and so developed amongst many of these insects, that it has been used against them for their own destruction. Thus amongst the means advocated for destroying a moth, _Botys sticticalis_, the caterpillars of which devour cereals and beetroot,[43] is the lighting of numerous fires in the fields. The moths, attracted by the light, fall in the flames and die in quantities.

When the usual swarms of may-flies emerge from the water, fishers make straw fires on their boats, and the insects singe their wings. The innumerable bodies incapable of flight fall into the water, and provide a coveted food for the fish.[44] This disharmonious and fatal instinct is displayed chiefly by nocturnal insects that rest during the day and do not leave their retreats till after sunset. In the cornfields Coleoptera of the genera _Anisoplia_ and _Rhizotrogus_, resembling each other in form and general appearance, are to be found. When a fire is lighted in the darkness of the night it is only the _Rhizotrogus_ that approaches it at the risk of its life. The _Anisoplia_ remains quiet in the midst of the corn. The latter kind of beetle pairs during the day, while the _Rhizotrogi_ satisfy their sexual desires during the night. Moreover, it is the males only of this species that fly about in the darkness and approach the fire, whilst the females rest at home in the plants.[45] It is probable, therefore, that light induces a sort of sexual excitement in these male beetles. The males, searching for the female, believe her to be in the midst of the flames, towards which they fly without being conscious of the danger they incur.

Such an interpretation of this disharmonious and suicidal instinct is confirmed by the fact that the moths attracted by fire are also almost exclusively males. Moreover, entomologists have advised against the lighting of fires by agriculturists in the belief that they destroy the noxious _Botys_, as they maintain that the females are not attracted. These latter therefore live on, and, being capable of laying eggs, produce a generation of voracious caterpillars.

Of the _Ephemera_ attracted by fire in such great quantities males are by far the more numerous. It is therefore really very probable that the mad excitement which leads to the destruction of so many male insects, represents a sort of sexual aberration. In this connection it is to be remembered that, amongst Coleoptera, species exist of which the females, hidden in the grass, produce intense light which attracts the males. In the common glow-worm, the female, which is devoid of wings, alone shines with the familiar greenish glitter. Even in species of which the two sexes are luminous, the female shines more vividly. It is true that there are some beetles with luminous larvæ, a fact that led Darwin[46] to remark that the production of light by insects may serve to frighten enemies. This is possible, and it is also possible that certain insects make use of their luminosity to light their way in the darkness.[47] But, notwithstanding this, the sexual character of the luminous organ is so manifest in certain species that it is impossible to doubt its function as a means of attracting the male.

In conclusion I may say that it is not my purpose at present to discuss the meaning of an instinct so fatal to insect life. I wish only to point out the frequency of the natural occurrence of disharmony, so that the satisfaction of an instinct is fatal to so many of its possessors.

It is plain that an instinct, or any other form of disharmony leading to destruction, cannot increase, or even endure very long. The perversion of the maternal instinct tending to abandonment of the young is destructive to the stock. In consequence, individuals affected by it do not have the opportunity of transmitting the perversion. If all rabbits, or a majority of them, left their young to die through neglect, it is evident that the species would soon die out. On the contrary, mothers, guided by their instinct to nourish and foster their offspring, will produce a vigorous generation capable of transmitting the healthy maternal instinct so essential for the preservation of the species. For such a reason harmonious characters are more abundant in nature than injurious peculiarities. The latter, because they are injurious to the individual and to the species, cannot perpetuate themselves indefinitely.

In this way there comes about a constant selection of characters. The useful qualities are handed down and preserved, while noxious characters perish and so disappear. Although disharmonies tend to the destruction of a species, they may themselves disappear without having destroyed the race in which they occur.

This continuous process of natural selection, which offers so good an explanation of the transmutation and origin of species by means of preservation of useful and destruction of harmful characters, was discovered by Darwin and Wallace, and was established by the splendid researches of the former of these.

Long before the appearance of man on the face of the earth, there were some happy beings well adapted to their environment, and some unhappy creatures that followed disharmonious instincts so as to imperil or to destroy their lives. Were such creatures capable of reflection and communication, plainly the fortunate among them, such as orchids and fossorial wasps, would be on the side of the optimists; they would declare this the best of all possible worlds, and insist that, to secure happiness it is necessary only to follow natural instincts. On the other hand, the disharmonious creatures, those ill adapted to the conditions of life, would be pessimistic philosophers. Consider the case of the lady-bird, driven by hunger and with a preference for honey, which searches for it on flowers and meets only with failure, or of insects driven by their instincts into the flames, only to lose their wings and their lives; such creatures, plainly, would express as their idea of the world that it was fashioned abominably, and that existence was a mistake.

As for man, the creature most interesting to us, in what category does he fall? Is he a being whose nature is in harmony with the conditions in which he has to live, or is he out of harmony with his environment? A critical examination is needed to answer these questions, and to such an examination the pages to follow are devoted.