A manual of obstetrics : theoretical and practical

Preface

The present Volume consists of the substance of a Course of Lectures which appeared in the Lancet in the year 1850. It has always been my custom to lecture either extemporaneously or from brief notes ; so that when in the autumn of 1855 I was asked to publish a Course on Obstetrics, I had but little time for preparation, and, with few exceptions, the whole was written in the year 1856. This, with the busy avocations of practice, involved no slight amount of labour, and may plead as some excuse for any shortcomings which may be evident to the critical reader.

I was subsequently invited by Mr. Churchill to re-cast the Lectures into the form of a Manual, as one of his Series ; and I willingly consented to do this, feeling there could be no higher object for a professional man than that of being as extensively useful as possible. I have been able to spare less time than I could have wished for this task, but I trust that some originality will be found in the work, and that it will contribute, in the hands of the student and practitioner, to the advancement of that branch of medicine of which it treats.

When I began to publish, I determined to give the authority for every woodcut taken from other works; I soon found,

VI

PREPACK.

however, that obstetric authors, of all countries, from the time of Mauriceau downwards, had copied each other so freely, without acknowledgment, as to render it difficult or impossible to trace the originals. I therefore relinquished the idea, and must content myself by stating that I have contributed in the present work upwards of twenty new engravings to the common stock.

I have to express my acknowledgment to many friends and practitioners who have furnished me with hints, advice, and cases, and especially I desire to mention the kindness I have received from my friends Dr. Matthews Duncan, Dr. Oldham, and Dr. Vernon.

Upper (Jrosvenor-street, April 19 th, 1858.

THE INDUCTION OF PREMATURE LABOUR 546

CHAPTER XLIY.

CHAPTER XLY.

CHAPTER XLYI.

EMBRYOTOMV 590

CHAPTER XLYII.

THE CESARIAN SECTION. — CHLOROFORM 605

CHAPTER XLYIII.

CONCLUSION 614

INDEX 627

MANUAL

OF

O B S T ETKICS.

Introduction

The knowledge of tlie modes of generation in different animals, of the anatomy and physiology of the parts concerned in reproduction in the human female, of the development of the embryo, and the pathological lesions to which the mother and ovum are liable, with the rules of practice derived irom observation and experience, constitute the foundation of the Science of Obstetrics. On the other hand, the Art of Midwifery consists ot the application of knowledge thus extensively derived, in the prevention and tieatment of the accidents and diseases incident to pregnancy, parturition, and the puerperal state. The object of both science and ait is the assurance of the safety of mother and offspring in these several conditions ; and it adds to the importance ol this biancli of medicine, that if any comparison of the value of one human life with another can properly be made, none is more precious than that of the woman in childbirth; for at no other time can the lives of two human beings be so closely united. Obstetrics have also an important relation to morals, since it sometimes happens, in the casualties of gestation and labour, _ that the lives of the mother and child come to some extent into competition, and the decision upon \\ hich the death ot the child rests, with a view to the safety of the mother, must be taken bv the accoucheur. These various considerations, no less than the scope of the subject itself, should imbue all who may be engaged in the study and practice ot this depaitment ot medicine with a sense of the responsibility under which they lie, to neglect no means of information which may contribute to make them sound and efficient practitioners.

B

INTRODUCTION.

In the Arrangement of the matter of the present volume, an attempt has been made to follow a natural method, placing those subjects which mutually illustrate each other as nearly as possible in juxtaposition. For instance, instead of treating of the pelvis and the frctal cranium at the commencement, these subjects have been treated of immediately before the mechanism of labour, with which they are so obviously concerned. In like manner, the deformities of the pelvis have been considered in the chapters preceding the subject of difficult labour from pelvic distortion. Indeed, throughout, without losing sight of a certain order or development, more has been thought of the mutual dependence of the various subjects upon each other, than of a strictly systematic method of proceeding.

By way of conclusion, the various causes of Death from Childbirth have been grouped together and compared ; and the means by which we may reasonably hope that the amount of mortality, both as regards the mother and child, will be considerably diminished hereafter, have been insisted upon.

Chapter I. Generation

In this the first chapter of a work on the Principles ancl Practice of Obstetrics, it is proposed to draw attention to some general considerations concerning the reproduction and development of living beings. Beginning with matters relating to the most simple modes by which the propagation of animals can be effected, we may easily ascend to the study of the higher forms of reproduction, until we arrive at the generation of the human species. It will be found, as we proceed, that there are no races so low in the scale of creation but that the history of their generative phenomena is calculated to throw light upon the same functions in classes of the highest rank in the animal kingdom. This circumstance must plead as an excuse for attempting to deal, at the commencement of the present work, with the elements or principles of generation.

At the very threshold of the subject, we are met by the long-agitated cpiestion of Spontaneous or Equivocal Generation. Can any form of animal life be produced upon the globe we inhabit, out of dead inanimate matter, or, indeed, otherwise than as part of a procession or series of living organisms, every generation of which must depend for its existence upon the generations that have preceded it ? In former times, many facts connected with the generation of the humbler forms of living matter seemed altogether inexplicable; and naturalists and physiologists were driven to a belief in the doctrine that, under special circumstances, such as the decomposition of animal ancl vegetable structures, some of the lower forms of animal existence might be developed spontaneously. The progress of knowledge lias, however, steadily diminished the number of these mysteries ; and it may be said that, in recent days, the last stronghold of the believers in spontaneous generation has been the conditions under which the Infusoria and Entozoa can be produced.

From any vegetable infusion, under certain regulations as regards light, air, and temperature, myriads of microscopical infusoria are called into existence. The same infusions uniformly produce the same animalcules, and the lowest forms of infusorial life are those which first appear. The results are the

n 2

•i

GENERATION.

same when water, which has been boiled or distilled, is used ; and observers of eminence have declared that they have seen thcdebris oi vegetable matter, while undergoing decomposition, transformed into infusoria. Others have believed that animalcules may be produced, by the action of electricity, from silica and similar inorganic matters, ft may, however, be said, at the present time, with regard to the infusoria, that the difficulties in the way of explaining their almost omnipresence have disappeared, and that their production, except under natural circumstances, can be satisfactorily disproved.

The different modes of propagation in the Infusoria have been investigated, and it is known that in their most simple forms, the perfect infusoria, and in other cases the germs, are almost innumerable, and of well nigh unextinguishable vitality. One animalcule, the Monas crepmculus, is -^oVo °f a ^ne m diameter ; and it is remarked by Professor Owen that a single drop of water may contain not less than five hundred millions of these minute beings. The drop evaporated, these vast populations, greater in number than the living inhabitant s of the world, become dry, and preserve their latent life in the air and in the dust of the earth, to be revivified on the occurrence of the conditions necessary to their existence. IN' ot a mote of the sunbeam but is peopled with these animalcular organisms. Their power of resisting destructive agencies is not one of their least wonderful properties. They live in water under ice, or enclosed in vesicles in the ice itself. Fontana revived some specimens of Kotifera after they had been exposed to the sun for upwards of two years in dry sand ; and Spallanzani and Schultze have revived them after four years of desiccation. Other animalcules, in drying, burst, and liberate myriads of germs, which preserve their vitality under almost every conceivable circumstance. These and similar facts prove that no particle of air, dust, or water cau be selected which does not contain infusoria or their germs, thus rendering it almost certain that the vegetable infusion does nothing more than favour the restoration of dried animalcules, or the development of their invisible germs. But the experiment inn cn/cis respecting the spontaneous generation of the infusoria has been applied by Schwann and Schultze. The access of air, which no doubt contains infusoria or their germs, is known to be necessary to the production of animalcules in vegetable infusions. One of these experimenters passed the air employed through caustic potash and through strong sulphuric acid ; and the other

GENERATION.

through iron tubes heated to redness, the infusions used having been previously boiled. Under these conditions no infusoria were produced, though a rapid development of animalcules occurred on the admission of air to similar infusions, when no such precautions were observed.

As regards the Entozoa, the presumptive evidence in favour of their spontaneous generation was still more conclusive than in the case of the infusoria. Entozoa are found in situations to which they could not be supposed to have access by any natural means, and particular entozoa are only met with in particular localities and organs. The Cysticercus cellulose is found in the anterior chamber of the eye, in the choroid plexus, and in the substance of the heart. The Trichina spiralis infests the voluntary muscles, and the Strongylus gigas the parenchyma of the kidney. A Diplostomum in the aqueous humour, has itself been found to be infested with parasitic animalcules. Entozoa have been detected in the foetus in utero, in the blood, and in the eggs of oviparous animals. Such facts appeared to present insuperable difficulties to the explanation of the existence of entozoa in their special habitats, unless upon the supposition that they are produced spontaneously. It came also to be known that many of the higher forms of entozoa possess complicated organs of generation, and produce ova and embryos in abundance, which themselves became the subject of observation. Eor a time, however, this knowledge only increased the difficulty. How, for instance, could entozoa reach the foetus, or enter the eye, when their ova were known to greatly exceed the diameter of the capillary vessels ?

It was at last discovered, that the entozoa, particularly in their embryo forms, possess a special boring apparatus, which had been noticed by John Hunter in some species, by means of which they are able to make their way through the solid tissues of the body with extraordinary facility, producing little or no disturbance in their progress, and leaving no traces of their operations behind them. It was also found that a vast variety of special provisions existed for the diffusion and localization of these creatures. The numbers, too, of the ova of some of the entozoa are immense. A single specimen of the Tania serrata, an entozoon which infests the dog, will produce twenty-five millions of ova ! while a mature female of the A. tear is lumhricoides will contain upwards of sixty millions ! Many of them pass through several phases of existence in

(i

GENERATION.

different animals before they arrive at the perfect state, provision being made for their transfer from one animal to another. It is believed that in every species of tape-worm, two animals are at least necessary for their complete development, and of these two animals, the one generally stands in the relation of food, or prey, to the other. Thus the scolex, or embryo head of the Tania crassicolis, is found in the mouse, while the perfect tsenia infests the intestines of the cat. The mouse is of course the means of introducing the embryo of the tsenia into the larger animal. The power of the entozoa in resisting destructive agents is even greater than the infusoria. Some of these worms of complicated structure remain alive after being boiled a considerable time ; others are re-animated after being frozen for several weeks. Their ova have still greater powers of selfpreservation. These and similar facts respecting their numbers, modes of generation, indestructibility, and powers of penetrating animal tissues, appear sufficient to explain all the seeming mysteries respecting the entozoa, without resorting to the theory of spontaneous generation.

The most simple form of animal life is that met with in the Fig. i. Gregarina;, a genus of microscopic entozoa found in the internal organs of worms and insects. The Gregarina consists essentially of a single cell, or of a cell-wall with its contained fluid, and a central nucleus. (Fig. 1.) It moves by contraction of its cell-wall, and only differs from a vegetable cell by the possession of contractility, and its solubility in acetic acid. In the simplest infusoria, the polygastrian animalcules, a class below the entozoa in the animal series, the same monadiform organization is found ; and throughout the infusoria, although many additions, in the shape of cilia and internal organs, occur, the type of a cell, with a central nucleus, or nuclei, is preserved. This central portion consists of hyaline matter, of an amber colour, which is supposed to be fatty in character, and is believed to bear a resemblance to the spermatic particles of higher animals. The Chlamydomonas may be cited as one of the simplest of these infusoria. (Fig. 2.)

The primary and most simple type of Reproduction, that which is found in these

Gregarina.

Fig. 2.

Chlamydomonas.

«. Hyaline nucleus.

GENERATION.

unicellular, monacliform animalcules, is that of spontaneous fission, or Fissiparous Generation, as it is called. In this mode ol' reproduction, in the most simple forms of infusoria, a single unicellular animalcule divides into two or more cells, which, after their division, become similar to the parent cell. The first infusorial animalcule ever known, the Vorticella convallaria, discovered by Loeuwenlioeck nearly two hundred years ago, multiplies itself in this manner. Sometimes the fissure takes place longitudinally, at others transversely (Fig. 3), a notch first appearing at the point of subse-

Fig. 3.

A, B, c. Longitudinal fission of elongated infusoria. D, E, F. Transverse fission of oval animalcules.

quent division, which enlarges until the separation is nearlycompleted, when the two cells straggle, by means of their cilia, until they are free from each other, and swim off as independent animalcules. In some infusoria the fission consists in a simple division of one cell into two. In others, they divide but still remain connected in groups, as a chain or in a spherical mass. The latter is the case with the Volvox globator , a well-known animalcule. Instances are metwith in which the divisions of succeeding generations are regular multiples of each other, as two, four, eight, and so on. This occurs, for instance, in the Chlamydomonas. (Fig. 4.) In the process of fission, the nucleus is

Fig. 4.

a, b, c. Multiple fission of Chlamydomonas. n. Nuclei.

GENERATION.

always the first part to divide, and it is this cleavage of the nuclear portion which rules the segmentation of the whole cell. In these simple organisms, the sperm and germ-force resides in the nucleus or nuclear particles — every nucleated infusorial cell, multiplying in this way, being, from its birth, as it were, impregnated and ready to propagate its kind by fission. No diminution of the reproductive force is caused by successive fissions, each generation of purely fissiparous animalcules having the same power as its progenitors. Many infusoria multiply bv other modes of generation as well as by fission, but the rate ot increase by this means alone is very great. The ParamcBcium aureliu, if well fed, divides every twenty-four hours, its progeny in successive generations continuing to divide in the same ratio. In this way, in the course of lour weeks, one animalcule will produce upwards of two hundred and fifty millions of new beings. This fissiparous mode of generation is found not only in the Infusoria and Entozoa, but in Polypi, Medusae, and the Annulata. It is in the infusoria also that the first acts of Parturition are observed. In the Loxodes Bursaria, four or five cells are formed in the interior of the animalcule, which are gradually developed into embryos. These embryos make their way slowly through the tissues of the parent and escape externally. No aperture or channel exists previously, and the situation of the parturient escape of the embryo seems entirely to depend upon accident. (Fin. 5.) At whatever part of the parent organism the embryo is developed, there a way is made for its escape. Sometimes two or three embryos are escaping from different parts of the parent at the same time. Prom this simple beginning, the extrusion of the ova and embryo goes on in the animal series, until it reaches the complexity and difficulty witnessed in the higher mammalia and in the human species.

The next form of reproduction met with in the animal kingdom is Gemmiparous Generation, in which the offspring arise from the parent in the shape of gemmae, or buds, which acquire a similar organization to the parent animal, and separate to assume an independent existence. In the Ht/dra tiridis, for instance, a prominence first appears upon the surface of the animal, which gradually assumes the form of a miniature polyp. It contains a cavity, which, in the first instance, communicates with the stomach of the parent Hydra. An oval aperture, surrounded with tentacles, is developed at its free extremity. At first the food digested in the stomachal cavity

GENERATION.

of the parent supplies the gemmule, but, after a time, the young polyp begins to catch iood, and contributes to the sup-

Fig. 5.

A, B. Formation of germs and embryos in Loxodes Bursaria. c. The process of parturition. D. e. Free, moving embryos.

port of itself and parent. At length, its connexion with the parent polyp becomes slender, and it separates altogether. (Fig. 6.) Another mode of gemmiparous generation is where, as in the sponges, small free gemmules, or buds, are separated from the body of the parent animal, and become developed into perfect individuals. The parts of the body from which gemmation takes place in different animals, are very various. In some, it may occur at any part of the surface of the body; in others, the gemmules are fonned in the digestive cavity, and extruded from the oral aperture. In the medusa;, the gemma; arise from the ovaries, stomach, proboscis, and tentacles. In other

GENERATION.

cases, as in tlie Alcyonidium elegans, aa Alcyonian zoophyte, the tubercles which constitute tne genuine, or buds, are pro-

Fio. 6.

A, B, c. Polypoid Acalephs, giving off gemma or buds.

duced in particular strips of tegumentary membrane. In some of the gemmiparous animals, new creatures may be multiplied to almost any extent by mechanical division. The Hydra viridis may be divided longitudinally or transversely into several parts, and each fragment will become a perfect polyp ; or if a wound is made in the body of the animal, a new polyp sprouts from the site of injury. The gemmiparous form of generation is met with in a iarge variety of animals. It exists in the Infusoria, Entozoa, Polypi, Medusae, Annulata, and Tunicata. In the Nereis, and in some of the Myriapoda, gemmation forms an important part of the reproductive process. In the former, a constriction first appears in the tail of the animal, immediately behind which the head of a new nereis is developed, and the posterior division becomes separated from the anterior, or parent nereis, as a perfect animal.

The earliest traces of a Dioecious mode of reproduction in animals, in which two individuals are engaged in the production of offspring, is met with in the humble Gregarina already mentioned, in what has been termed Conjugate Generation. These microscopical entozoa propagate not only by fission, but by a process termed conjugation. In the latter mode of generation, two of the elongated cells or animalcules are said by Stein and other observers to approach each other ; the two ends which are in opposition become flattened, so that the two conjoined animalcules resemble a single Gregarina in shape. A complete fusion of the granular contents of the two individuals takes place, and from the joint mass a number

GENERATION.

of small bodies are produced, which are believed to be the embryos of this monadiform entozoon. (Fig. 7.) Other in-

Fig. 7.

Conjugation of Gregarin®. a. Single Gregarina. b, c, d. Two animalcules in a state of conjugation, e, f, g. Formation of embryos, h. Free embryos.

stances of conjugate generation have been observed by Kolliker, Siebold, and Cohn. This mode of generation appears to be quite wanting in anything of an ordinary sexual character. The conjugating Gregarinaj appear to be precisely similar to each other, and their reproduction seems to be by a kind of duplicate fission. It is, however, impossible not to be struck with the similarity of the process of conjugation, and the union of the sperm cell and germ cell in the higher animals, to which sex has been added in the scheme of reproduction. In the latter case, the sperm and germ cells unite to produce, by division and subdivision, the particles forming the germ mass, out of which the embryo is evolved. As soon as sexual generation commences, two kinds of cells arc required in the process of reproduction — one produced in the ovarium, the

GENERATION.

other in the testes. In the lower classes, these t wo organs are frequently found upon the same individual, constituting com- 1 plete hermaphrodite generation. In other instances the individuals are hermaphrodite, but the mutual congress of two or more animals is necessary for fertilization- In the higher classes hcrmaphrodism disappears, and the ovarium and testis, | with the sperm cell and germ cell, belong to different animals and sexes.

The present seems to be the proper place for making some general remarks on the subjects of Fissiparous and Gemmi- •- parous Generation, and the relation of these processes to the j acts of reproduction in the higher animals. The principle of I fission is not limited to "animals in which it constitutes the j chief mode of generation. It extends in a certain degree to ] the higher forms of animal reproduction. In oviparous animals ] and mammalia, it may be said that the dehiscence of the ovule, i or of the impregnated ovum, from the ovarium, is a kind of ] fission. A still closer analogy to the phenomena of fission is found in the early changes in the interior of the mammalian 1 ovum after impregnation, and indeed of the ovum of all animals multiplying by sexual generation. (Fig. 8.) These changes i

Development of Ascaris acuminata by repeated fission of the germ cell. Type of development in all animals produced from ova.

are similar to those which have been referred to as occurring in the unicellular infusoria. That which will hereafter have to be described as the segmentation or cleavage of the yolk, consists in the division ancl subdivision of the embryo cell, and

Fig. 8.

GENERATION.

is almost identical with the multiple fission of the Chlamydoxnonas — an analogy first pointed out by the late Dr. Martin Barry. The only difference is that in the Chlamydomonas and Greg iritia the divisions and subdivisions produce independent and perfect animals; whereas in the mammalian ovum the fission results in a mass of germ cells, intended to pass on to Iiigher developments. In animals the subjects of sexual generation, the male element is also formed by the rupture of the primary germ cells secreted by the testes, and the conversion of their nuclear matter into spermatozoa, which may, in fact, be considered as secondary germ cells. It may also be said that the human fabric is the result of the fission, an innumerable number of times repeated, of the single fertilized embryo cell; the multitudes of cells produced by the rupture and fission of generation after generation of cells, and by the conversion of their nuclei iu turn into parent cells, being moulded by plastic morphological forces, into bone, muscle, nerve, blood, and the other elements of which the body is composed. The similarity of the ciliated epithelial cell of the mucous membranes, to the ciliated unicellular infusoria is very palpable. It is of myriads of such cells, modified in infinite ways, that the human organism is constructed. In this way we can to a certain extent realize the idea of Buffon, when he said that all animal and vegetable bodies were aggregations of animalcules ; or the more positive remark of Olcen, that the Iiigher animals, and man himself, were agglomerations of infusoria.

Generation by means of buds or gemmae is still more extensive than reproduction by fission. In gemmiparous animals (reproductive nuclei are scattered throughout the structures ■ and tissues of the parent organisms; it is a fission occurring, mot, as it were, in the whole animal, but in particular parts. The mode of reproduction by gemmation extends higher than ifissiparous generation, being found, as we have said, as high i as the Tunicata, and it is concerned in that peculiar form of i reproduction termed Alternate Generation, which is found i amongst insects. But the principle of gemmation is not lost at the point when it ceases to be a mode of generation. It is i concerned in the reproduction of lost parts. In gemmiparous generation, animals are formed, not from ova, or from the fission of primary reproductive cells, but from secondary or 1 derivative germ cells, placed in reserve in the tissues of animals. In the triton, or the lobster, in which the tail or claw

GENERATION.

is reproduced, the new formation occurs from derivative gem cells placed in the tail or claw — that is, a reserve of derivative germ cells, not used in the general development, is deposited in different parts of the body, and come into use when regeneration follows the loss of particular parts or organs. In mammalia, the extremities in the feet us are always formed by budding or gemmation. It is believed by some observers that in the human foetus, if a limb be amputated spontaneously in utero, at an early period, there is an attempt at the production of a new limb by gemmation. In some of the remarkable cases of spontaneous amputation of limbs in utero, first investigated by Dr. Montgomery and Prof. Simpson, the amputated limb is found in the uterus, and from the stump, small or rudimentary fingers or toes are seen to be growing, which remain visible in after life.

One of the most remarkable phenomena in the history of reproduction is that of alternate generation, first investigated by Bonnet, Reaumur, Steenstrup, and others, and to which great significance has been given by Prof. Owen, under the name of Parthogenesis, or virgin-procreation. In many forms of animal life — as, for instance, in the Salpae amongst 1 mollusca, the Distomata amongst entozoa, and the Aphides amongst insects — it is found that the parent animal gives birth to an embryo different to itself; that this embryo lives as an independent animal, but gives birth, without sexual intercourse, to another, and to a successive series, until at length a progeny is formed bearing the likeness of the original parent.

The observations of Agassiz go to prove that the infusoria generally are only the ova of the entozoa, the polygastric animalcule being the larval condition of the parasitical worms. In the Distoma, the embryos have at first the form of ciliated monads, and these are metamorphosed into Gregariniform worms. In the interior of each of the latter, numbers of Cercariform, or tailed animalcules, are developed, which in turn become true Distomata. In the winged Aphis, the ova are deposited by the parent insect, and in due time produce larval, wingless aphides. Each virgin aphis of this brood will produce other similar broods, without contact with the male. ' This Lucina sine concuhitu has been observed to go on to the eleventh generation, the last generation being winged, and i male and female. These have intercourse, another fecunda- ; tiou occurs, and in the following summer the phenomena ! which have been described again occur.

GENERATION.

The explanation of these cases is, that in the first instance the coitus fertilizes the ovum, and part of the derivative germ cells produced from the embryo cell, instead of being consumed in the development of the first generation of aphides, are kept as a reserve. In the second generation, these derivative germ cells give origin to a new generation of derivative germinal cells, of which a reserve remains as before, and so on until the spermatic force of the germ cells is exhausted. To illustrate this matter, let us look to the early development of the mammalian ovum. The embryo cell divides into two, these two into four, the four into eight, and it is not until the segmentation has affected the whole mass of the germ and yolk that the formation of the new individual begins. But suppose each generation of germ cells, occurring in this fission ■ or segmentation, to have the power of going on to the production of new individuals, we should then have the power i observed in the virgin aphides, where each generation of germ > cells goes on to the production of a larval aphis before a new t fission or segmentation of the derivative germ cells takes place. We may see traces of this power of the spermatic ' element, to fertilize or modify more than one generation of ova and germ cells, in other animals than those in which perfect parthogenesis occurs. For instance, a single coitus of the i cock fertilizes, not only the eggs which are mature in the ovary, but those which are immature, so that eggs which reach maturity a long time after coitus are found to be fertilized. The parthogenetic influence may, I think, even be seen in the mammalia and in the human female. In the well-known case of the mare covered by the Quagga, the foals produced afterwards, by intercourse with her own kind, still bore the stripes of the quagga. In the human female, it is found that a woman having married and borne children by her husband, becomes a widow, marries a second time, and bears children to her second husband which have the lineaments of her first husband. The same occurs in the lower animals, and it is difficult to explain the matter in any other way than by supposing that one coitus must have influenced several generations of ova. The relation of such phenomena to parthogenesis is obvious.