It is known that there is a great difference in the stability of type in different species of plants and animals that have been subjected to cultivation. One produces striking varieties in a single generation; another requires careful selection of certain characters for many generations before well-marked varieties can be secured. We also know that continued cultivation will, in many instances, break down the stability of type in a species that, in the first place, adhered with great persistency to one form. It often happens that when the stability has once been disturbed, a wide range of variation may afterwards be obtained with comparative rapidity.

    Is it not possible that similar changes may sometimes take place in species in their wild state? Two important elements of the cultivation which tends to develop varieties are the removal of competitors and enemies, and the abundant supply of nourishment; but both these conditions may sometimes be furnished by nature without the intervention of man.

    The more severe the competition the more rigidly does Natural Selection adhere to the one form that is best suited to meet that competition, or, according to the language in which Professor Owen has stated the doctrine, the more certainly does the "Battle of Life" extinguish all variations from that one form. When a species is subjected to severe competition of the same kind for countless generations, we may well believe that it gains a stability of type that is not found in one that has during the same time been, either comparatively free from competition, or under the influence of a succession of different competitors and enemies*. {Footnote: The only terrestrial mollusks with which the Achatinellinae have to compete are a few Helices much inferior in size, and not arboreal in their habits.}

   1st. By Freedom from the Competition that Limits Variation. -- We can see that when animal life commences upon an island where vegetation has already become abundant, the first species that appears on the arena, unless immediately followed by other creatures capable of being either friends or foes, will enjoy for a time complete freedom from competition. If the vegetation is suited, it will also have an abundance of food. Under these circumstances every variation that occurs, unless decidedly malformed, will have a chance of living and exerting an influence upon the final result.

   2nd. By Competition Accelerating Variation.-- If the introduction of competitive animals is long delayed, the first struggle for life will occur between the members of the one stock. But competition of this kind does not tend to prevent variation, but rather to accelerate it, by driving portions of the race into new spheres. Supposing the animals first inhabiting the island to be a species of arboreal mollusks, there would soon be an excess of occupants on the trees best suited to them in the region where they first appeared. The portion of the population that would survive this exigency would, in the first place, be those that found sustenance on trees of other kinds, Some of these would either themselves, or through their descendants, reach localities where the trees are again found on which the stock commenced its career. Those that, in this way, returned to the original trees, would have acquired some new tendencies to variation through the ordeal through which they had passed; and those that remained upon the other kinds of trees would rapidly develop new characters: in either case, there would be no outside competition limiting them to one definite form. New forms of variation would have an opportunity of being preserved. New shades of colour, for example, would not expose the owners to the attacks of enemies. Variations of shape, if not inconsistent with the pursuit of food, would be no disadvantage.

    3rd. By Continual Change in the Character of the Natural Selection. -- Still further, we can see that when competition arises from the gradual introduction of animals, either friendly or hurtful to the first occupants, the character of the Natural Selection, to which they would thus be subjected would be continually changing; no one set of characters would have constant advantage through a long series of successive generations.

    In these ways the persistence of form might be impaired, and the variability which we may believe exists in some degree in all organisms might be greatly increased beyond what is usually found. This tendency to comparatively rapid variation having been established, the evolution of species would be correspondingly rapid, and the areas of each proportionately limited.

    If a bird should carry a leaf bearing two individuals of some species and drop it a mile beyond the limits already reached by others of that species, they might there find the same trees to which they were accustomed, and multiply for some tens of years before the first scattering individuals from the slowly advancing wave of migration would reach them. They might, by this time, have increased to many thousands; and having been entirely separated from the original stock for a considerable number of generations, with a preexisting tendency to rapid variation, a certain variety of form and colour might have partially established itself amongst them. The arrival of a few individuals representing the old stock would, amongst the multitudes of the new variety, have no influence in bringing back the succeeding generations to the original form. The new characters would become from year to year more distinctly set. Owing to an intervening ridge acting as a partial barrier, the number of individuals of the original stock coming amongst them might be always restricted; and even if no such barrier existed, the individuals arriving from abroad could never be more than a very small number compared with those produced on the spot and possessing the local characteristics.

    At this point one other inquiry naturally arises: -- If the multitude of varieties and the restricted distribution of both varieties and species is in any degree due to freedom from severe competition, what would be the effect if, by degrees, many birds and insects, hostile to these snails, should find their way to the Sandwich Islands and become numerous in those mountain-regions? One of the first effects would naturally be the disappearance of many varieties and species by which the different forms of each genus are now so minutely gradationed together. Certain protective colours would be made to prevail, to the partial exclusion of some of the brilliant contrasts of colour. The same enemies being found in all the valleys of an island, the forms that proved to be best fitted to survive in one valley would have the advantage everywhere, and therefore gradually spread from valley to valley. The distribution of species and their separation from each other by distinct forms would thus become similar to what is found in the case of continental species.

    The destruction of forests by the introduction of cattle and goats is now causing the extinction of some of the species.

   A comparison of the distribution of island mollusks with the widely contrasted distribution of continental species, leads me to believe that the evolution of many different species may take place without any difference in the food, climate, or enemies that surround them. The rapidity of evolution, or the time within which a certain amount of change is effected, must depend upon the average amount of change in one direction in a single generation, and the rapidity of succession in the generations. Ten thousand years would make but little difference in a species of cedar, in which the life of a single tree might count a third of that period. But in the case of some species of insects the same period might cover ten thousand generations; and though the change in each generation might be as imperceptible as in the cedar, the aggregate of change for the whole period might be very apparent.

    We must also bear in mind, the Natural Selection arising from severe competition with species that have a wide range tends to prevent variation and give a wider diffusion to forms that would otherwise be limited in their range and variable in their type. Natural Selection is as efficient in producing permanence of type in some cases as in accelerating variations in other cases.

    It we suppose separation without a difference of external circumstances is a condition sufficient to ensure variation, it renders intelligible the fact that, in nearly allied forms on the same island, the degree of divergence in type is in proportion to the distance in space by which they are separated. The difference between two miles and ten miles makes no change in climate; but it is easy to believe that it is the measure of a corresponding difference in the time of separation. In forms that differ more essentially, the separation may have been as complete and as long-continued in the case of those which now inhabit one valley as in the case of those which are separated by the length of an island. When a wide degree of divergence has been established, hybridation would be precluded. We accordingly find that the difference between species of different genera or subgenera is in most instances equally great whether we take for comparison those from the same or from different valleys.

    If, on the other hand, we suppose that a difference in the external conditions is necessary to the evolution of distinct forms, these and other similar facts remain unexplained.

From Chapter 11 of The Naturalist in Nicaragua,  pages 206-209

by THOMAS BELT. Published by John Murray, London (1874).[Words in square brackets by DRF]

   Tschudi makes [describes] two races of indigenous dogs in tropical America. 1. The Canis caraibicus (Lesson), without hair, and which does not bark. 2. The Canis ingae (Tschudi), the common hairy dog, which has pointed nose and ears, and barks.* {Footnote: J. J. von Tschudi, quoted by Humboldt, [in] "Aspects of Nature", English edition, vol. i, p. 111.} 

   The small eatable dog of the Mexicans was called by them Techichi; and Humboldt derives the name from Tetl, a stone, and says that it means "a dumb dog," but this appears rather a forced derivation. Chichi is Aztec for "to suck"; and it seems to me more probable that the little dogs they eat, and which are spoken of by the Spaniards as making very tender and delicate food, were the puppies of the Xoloitzcuintli, and that Techichi meant "a sucker".

    Whether the hairless dog was, or was not, the Techichi of which the Mexicans made such savoury dishes is an open question, but there can be no doubt that the former was found in tropical America by the Spanish conquerors, and that it has survived to the present time, with little or no change. That it should not have intermixed with the common haired variety, and lost its distinctive characters, is very remarkable. It has not been artificially preserved, for instead of being looked on with favour by the Indians, Humboldt states that in Peru, where it is abundant, it is despised and ill-treated. Under such circumstances, the variety can only have been preserved through not interbreeding with the common form, either from a dislike to such unions, or by some amount of sterility when they are formed. This is, I think, in favour of the inference that the variety has been produced by natural and not by artificial selection, for diminished fertility is seldom or never acquired between artificial varieties.

    Man isolates varieties, and breeds from them, and continuing to separate those that vary in the direction he wishes to follow, a very great difference is, in a comparatively short time, produced. But these artificial varieties, though often more different from each other than some natural species, readily interbreed, and if left to themselves, rapidly revert to the common type. In natural selection there is a great and fundamental difference. The varieties that arise can seldom be separated from the parent form and from other varieties, until they vary also in the elements of reproduction. Thousands of varieties probably revert to the parent type, but if at last one is produced that breeds only with its own form, we can easily see how a new species might be segregated. As long as varieties interbreed together and with the parent form, it does not seem possible that a new species can be formed by natural selection, excepting in cases of geographical isolation. All the individuals might vary in some one direction, but they could not split up into distinct species whilst they occupied the same area and interbred without difficulty.

    Before a variety can become permanent, it must either be separated from the others, or have acquired some disinclination or inability to breed with them. As long as they interbreed together, the possible divergence is kept within narrow limits, but whenever a variety is produced the individuals of which have a a partiality for interbreeding, and some amount of sterility when crossed with another form, the tie that bound it to the central stock is loosened, and the foundation is laid for the formation of a new species. Further divergence would be unchecked, or slightly checked, and the elements of reproduction having begun to vary, would probably continue to diverge from the parent form, for Darwin has shown that any organ in which a species has begun to vary, is liable to further change in the same direction.* {Footnote: See "Animals and Plants under Domestication," vol. ii. p. 241.     

    Thus one of the best tests of the specific difference of two allied forms living together [i.e. whether they are distinct species], is their sterility when crossed, and nearly allied species separated by geographical barriers [not necessarily associated with a sterility barrier] are more likely to [successfully] interbreed than those inhibiting the same area [where a sterility barrier would be expected]. Artificial selection is more rapid in its results, but less stable than that of nature, because the barriers that man raises to prevent intermingling of varieties are temporary and partial, whilst that which nature fixes when sterility arises is permanent and complete.

    For these reasons I think the fact that the hairless dog of tropical America has not interbred with the common form, and regained its hairy coat, is in favour of the inference that the variety has been produced by natural and not by artificial selection. By this I do not mean that it has arisen as a wild variety, for it is probable that its domestication was an important element amongst the causes that led to its formation, but that it has not been produced by man selecting the individuals to breed from [amongst those] that had the least covering of hairs. I cannot agree with some eminent naturalists that the loss of a hairy covering would always be disadvantageous. My experience in tropical countries has led me to the conclusion that in such parts at least there is one serious drawback to the advantages of having the skin covered with hair. It affords cover for parasitical insects, which, if the skin were naked, might more easily be got rid of.

INUTILITY OF CHARACTERS.  PARADOX OF SEX.  RANDOM DRIFT

A translation from French and German by Polly V. Forsdyke and Donald R. Forsdyke of a foray into evolution of the polymath Joseph-Remi-Leopold Delboeuf (1831-1896), best remembered for his contributions to neurophysiology (see D. J. Murray (1993) A perspective for viewing the history of psychophysics. Behavioural and Brain Sciences 16, 115-186; S. Nicolas, D. J. Murray & B. Farahmand (1997) The psychophysics of J-R-L Delboeuf. Perception 26, 1297-1315.)

A Law of Mathematics Applicable to the Theory of [Biological] Transformation

By J. Delboeuf, Professor at the University of LiEge, Belgium.

La Revue Scientifique de la France et de l'Etranger. (1877) Second series-Volume 12 (Volume 19 of the collection). pp. 669-680. Also published in Kosmos (1877) Volume 2, pp. 105-127.

I. First statement of the problem: How can an advantageous transformation occur?

II. Second statement of the problem: How does disadvantageous transformation occur?

III. General Statement of the Problem.

IV. Solution of the Problem

V. Conclusion and Further Observations

I. First statement of the problem: How can an advantageous transformation occur?

Of the various criticisms which can be applied to a new doctrine, without doubt the most penetrating are those resting on mathematical grounds. The transformation doctrine invites criticisms of this nature. To introduce the problem, I can do no better than relate the views of Mr. Paul Janet, upon which my argument is based. In his beautiful book, Final Causes, a work of distinct historical insight, he expresses his doubts and reservations as follows:

"The true basis of Darwin's Theory is the extrapolation from artificial selection to natural selection; this establishes how blind nature by the chance combination of circumstances achieves the same result as man achieves through design."

Man selects the factors of reproduction; for example, he selects the male and female who possess a particular character he desires to fix; but how exactly, in nature, can the male discover the female who possesses the same endowment [genre de superiorite] as himself? Without hesitation, Darwin invokes the struggle for existence in which only the strongest and most able survive. However, this new principle is not a sufficient explanation.

"Let us suppose, as a fact, that in hot countries skin colour is an advantage which makes the inhabitants more able to bear the rigor of the climate; let us suppose further that in one of these lands there would be only white people and, at a given moment a black man accidentally came into being. Clearly, he would have an advantage over his compatriots; if you wish, assume that he would live longer.

    Should the man marry, what type of women would he take? Without doubt a white woman, since there would have been no other choice. Would the child who resulted from this union be black? Without doubt it would be mulatto. The child of this child would be a further one tone paler, and so the accidental colour would after some generations disappear and lose itself in the common characteristics of the race. Thus, although the dark colour would be an advantage, it would never have been able to perpetuate so as to create a new variety better adapted to the climate, and which could displace the whites in the struggle for survival."

Every radical departure from the normal, according to Mr. de Quatrefages, will lose something of its influence in every successive generation due to it's fusion with the normal.

    Mr. Paul Janet next cites a passage from an article which appeared in the Revue Scientifique. Here, an English scholar, Mr. Bennett, applies this line of reasoning to another example. I can do not better than reproduce the passage in its entirety: Here, an English scholar, Mr. Bennett, applies this line of reasoning to another example. I can do not better than reproduce the passage in its entirety:

"In his book, The Influence of Selection, Wallace cites a very curious case of this type (a case of mimicry, that is to say, imitation), concerning a species of South American butterflies related to our own cabbage-white butterflies (pierides), members of the species Leptalis. In general, birds are very fond of pierides. In contrast, they almost never attack the butterflies of the family Heliconidae, which are represented by the species Ithomia in South America. The reason for this disdain is that the Heliconidae release a nauseating liquid when they sense danger which makes them the most unpleasant of foods. Now it so happens that certain types of Leptalis, without losing any of their essential characteristics, take on exactly the colour which would cause an untrained eye to confused them with the real Ithomia. With such a disguise, they escape the pursuit of their enemy much easier than their white coloured relatives. Wallace attributes to natural selection the creation of this protective form of Leptalis. This conclusion is attacked by Mr. Bennet using a line of reasoning which appears to us most rigorous. "It is clear," he says, "that, in order to pass from their usual form to the protective form, Leptalis must undergo a series of gradual transformations, and one can hazard a guess that no less than a thousand intermediary forms must have occurred between the original deviation and the ultimate form. On the other hand, it is clear that the first deviating Leptalis was not different enough from it's sisters to confuse the appetites of interested birds, who could see through their disguise. It is reasonable to believe that during the first fiftieth of the transformation period, supposing it continuous, the birds would not have been misled. If this is so, then the butterflies would not be at all preserved by their changed appearance, the basis for selection would disappear, and the continuation of the transformation process would be a matter of chance. These chances can be very approximately calculated.

    For example, let us take a pair of Leptalis and suppose that the species had the tendency to vary in twenty different directions of which only one tended towards that of Ithomia. In the first generation the chances of a favorable deviation would be represented by the fraction 1/20 and this evaluation is favorable to the Wallace hypotheses, because among the numerous progeny of a pair of butterflies, one would certainly find more than 20 forms, even if only just a little different, which would distinguish themselves from the previous form.

    In the second generation the forms that already had the tendency to deviate towards the Ithomia form would have no reason to regress and it would be just among this 20th of the descendants of the original couple that we can reasonably expect to find forms that more of less approach the protective form. But for this 20th selection is still not effective, and it is still chance that determines the pressure towards the form in question; only 1 in 20 of the offspring of the new descendants will assume this form; but these will only represent a 20th of the 20th of the offspring of the original couple. The chances of finding useful forms in this second generation can be represented by the fraction [1/20]² , or 1/400. After ten generations, the chance will reduce to [1/20]¹⁰; this means that in every ten billion individuals just one will conserve traces of the original deviation, and we are not even halfway through the generations which compose the first 50th of the transformation period. This being so, when we apply this calculation to the total population of a district that we estimate at one million, we find only a single individual of the species Leptalis among 10 millions which after 10 generations have elapsed since the first deviation, can present a few characteristics similar to those of Ithomia: this is an absolutely negative result and forces one to reject completely the hypothesis of selection, since, before this could have acquired any validity, the original chance variation that was favourable to the survival of the individual would have completely disappeared among the mass of opposing variations.

     This conclusion carries even more weight in the situation of deviations tending to approximate the form of an animal to one very distant to itself, or even to inanimate objects. One must therefore look elsewhere for the cause of the phenomenon of mimicry and one might, as Mr. Bennet suggests, find it in instinct itself. --  Mr. Bennet, without being opposed to natural selection, precisely defines the boundaries of its influence; it can do much for the transformation and especially for the fixation of species; but it is not capable of everything and the most enlightened advocates of Darwinism cannot deny this viewpoint".

    One sees that the conclusion of Mr. Bennet is exactly that of Mr. Paul Janet. In his discourse, referred to above, Mr. Broca presents similar objections. They will be dealt with shortly. Not wishing at this time to comment on the merits of the problem, nor to defend Mr. Wallace's theory, I will remark that the reasoning is not so peremptory as it may seem. On the same premises, I will later come to completely opposite conclusions.

    When one deals with mathematical formulas, it is necessary to be aware of the nature of the problem and its associated facts. A mistake in the case of equations carries serious consequences and such a mistake was made here. This is all the more frustrating since much mathematical reasoning assumes an air of infallibility, and he who uses it deserves some deference due to the quality of absolute certainty associated with arithmetic and algebra. One does not dare to contradict when one is placed in his territory and further find that all the advantages are in his favour. But, before we directly tackle the subject, let us complete the set of objections which, in this scheme, oppose transformation.

II. Second statement of the problem: How does disadvantageous transformation occur?

    If one has understanding well the implication of the observations just described, one would have noticed that they tend to outline the impossibility of conceiving species transformation from a given trait to a more advantageous trait. However in living nature there are also transformations of the opposite sense, and those which are more or less indifferent; for the soundest reasons they also seem incapable of explanation by natural selection. Mr. Broca states:

"The orangutan is alone among the primates in having no toe-nail on its big toe. I ask the Darwinians how this bizarre character could have been produced. They answer that one day a certain monkey was brought into the world without a big toe-nail, and that this variety of individual is perpetuated among its descendants.
   For more clarity, let us give a name to this 'big toe-nailless' pythecian ancestor; since he was the origin of the Satyrus species, let us name him Prosatyrus 1st, giving him a number to signify his role as founder of a dynasty. Prosatyrus the 1st had a certain number of offspring of which a few doubtless resembled their other ancestors in having, like them, a nail on every toe. However, by virtue of the law of immediate inheritance, one or many of them would have been, like their father, born without a nail on their big toes; then, thanks to natural selection, this character became more and more frequent among the descendants of Prosatyrus the 1st, and eventually a time arrived when it had became a constant character.
    I ask myself, indeed how it could be that the absence of a big toe nail could have been given preference by natural selection; I do not see how this negative characteristic which did not improve any function, could have given to individuals so endowed an advantage in the struggle for existence. I would rather assume the contrary. I therefore cannot explain the success of the line of Prosatyrus the 1st; but one cannot understand everything, and I would like to attribute to natural selection the merit of having fixed this characteristic among the ancestors of our orangutans.
    However the orangutan distinguishes itself further from all other primates, living as well as fossils, by the absence of the round ligament of the hip. This odd ligament, which has no analog in any of the other joints, is not only found in all the primates, but also in most mammals, and it's absence in orangutans can be considered an anomaly. The Darwinians could, with some appearance of reason, attribute the appearance of this character to an individual deviation which came about by chance in the ancestors of the orangutan, and eventually became a fixed through natural selection.
    I continue to ask myself how natural selection and the struggle for existence could allow the endurance of a disorder that is more harmful than helpful to the operation of the coxo-femoral joint? Nonetheless, I continue to answer by saying that one cannot explain everything, and I confine myself to asking the following question: At which point in time did the absence of this ligament reveal itself among the ancestors of the orangutan species? Was it before or after the existence of the one I have named Prosatyrus the 1st?
     Let us first see if this first monkey without round ligaments was one of the descendants of Prosatyrus the 1st. If it was thus, then it would be appropriate to give the name "Prosatyrus II" to the one who, among the big toe-nailless monkeys, inaugurated this seconded distinctive character of the orangutan species.
     By the time that Prosatyrus II came into the world without his round ligament, a certain number of generations had already passed since the big toe nail had disappeared. It is by hundreds that one counts the descendants of Prosatyrus the 1st who, like him, were missing their big toe-nails but still bore round ligaments.
     It was from this large cohort of individuals resembling Prosatyrus the 1st that Prosatyrus II emerged successful in the struggle for existence. He was different from them only in lacking the round ligaments, a feature which was in no way an advantageous to him. I willingly admit that despite this defect, he was able to live until an adult age and was able to conceive of some offspring resembling himself, and that these, mating among themselves (I don't know how), created a variety characterized by the lack both of big toe-nails and of round ligaments, but there is no reason why this variety should have displaced the other, no reason why the numerous representatives of the variety of Prosatyrus the 1st should have lost their right to exist.
     Let us suppose that there were only a thousand or even just a hundred at the time of the birth of Prosatyrus II; these were dispersed over a wide area, mostly situated beyond the area where Prosatyrus II lived, and all would have had more or less the same chances of reproducing as Prosatysus II. They would have had descendants resembling themselves and, since the variety Prosatyrus II was able to maintain its existence despite its imperfection, the variety Prosatyrus the 1st would have been a hundred, even a thousand times more numerous, and, do not forget, better constituted, a strong reason for their survival. There must therefore have been co-existing with the orangutans lacking both the big toe-nails and the round ligaments, another variety, which, while similarly lacking the big toe-nail, still possessed the ligaments. Of the variety that would have existed if the round ligament had disappeared after the big toe-nail, there is no trace. This intermediary species does not exist; consequently it is not possible to agree that the round ligament was lost for the first time among the descendants of Prosatysus the 1st."

    The author further notes the other possible assumption, that the round ligament disappeared before the first toe-nail, is no more admissible than the other. Consequently, they disappeared at the same time, and Prosatyrus the 1st, doubly defected, was born on one occasion without both round ligaments and the first toe-nail.

     But the orangutan possesses further unusual characteristics: his lungs are individual, that is, each of his lungs contains only one lobe; furthermore, alone among the primates, it has only sixteen dorso-lumbar vertebrae. Applying to these special characteristics the above line of reasoning, one comes to the conclusion that Prosatyrus I must have been born at an instant with all of the characters of the species Sartyrus; that is to say, that there was no transition, no progressive transformation, but:

"a complete instantaneous transfiguration, contrary to all laws, Darwinian or otherwise; let us not shrink from the word, it is a supernatural act, equivalent to an act of creation."

    Mr. Broca's argument is more or less plausible, and the Darwinists can hardly escape it without recourse to further hypothesis. Meanwhile, one could remark that he assigns to natural selection the insignificant characters created in Prosatyrus I, which he ignores as soon as he deals with the formation of Prostysus II. Moreover, the conclusion, perfectly legitimate in its essentials, contains debatable elements. There was not necessarily "a complete instantaneous transfiguration", it could also be that the transformation occurred slowly and acted collectively on the four distinguishing characteristics of the orangatan by virtue of the mysterious laws of the correlation of growth. But, I repeat, the main point remains the method of fixation of these seemingly indifferent characters. Let us now take this line of reasoning and apply it to the appearance of characters which are disadvantageous with respect to the struggle for existence; and let us choose, as example, a particular, but sufficiently general case.

     The completely inferior animals, which one can reasonably view as the closest to the primitive types, reproduce themselves by division or fission. This method of reproduction is followed in the more advanced species by more complicated methods which function either in concurrence with the former or in isolation from it. Among the myxomycetes, at a certain moment in their evolution, separate individuals reunite themselves in order to form a certain type of spore which, in turn, creates zoospores, that is, capsules from which new distinct individuals emerge. Among other living species, Botrydium for example, there are generally two individuals who unite in order to form a new being; and that is obviously where we find the first glimmer of sexuality. Thus, there appear successively:

• perfect hermaphrodism (allowing an individual to produce, without the help of another, an individual resembling itself), then
  
• imperfect hermaphrodism requiring a mutual pairing for reproduction, and eventually the
  
• absolute separation of the sexes.

   

  At first glance, one would be inclined to conclude that the most favourable condition for the continuation of the species would be that in which the individuals of the species reproduce themselves by fission or, at least, that they are perfect hermaphrodites. However, actually perfect hermaphrodism is the exception and sexuality is the rule. By virtue of which law did the separations of the sexes become predominant in nature, when, contrarily, everything seemed to be opposing its expansion? How did seemingly advantaged species cede their positions to other seemingly most disadvantaged species? Above all, this is where the principle of Natural Selection fails.