--Publishers' note

** Magendic's Physiology.--Author's note.

The part performed by the female in the reproduction of the species is far more complicated than that performed by the male. It consists, in the first instance, in providing a substance which, in connection with the male secretion, is to const.i.tute the foetus; in furnishing a suitable situation in which the foetus may be developed; in affording due nourishment for its growth; in bringing it forth, and afterward furnishing it with food especially adapted to the digestive organs of the young animal. Some parts of this process are not well understood, and such variety of hypotheses have been proposed to explain them that Drelincourt, who lived in the latter part of the seventeenth century, is said to have collected two hundred and sixty hypotheses of generation.

It ought to be known that women have conceived when the s.e.m.e.n was merely applied to the parts anterior to the hymen, as the internal surface of the external lips, the nymphae, etc. This is proved by the fact that several cases of pregnancy have occurred when the hymen was entire. The fact need not surprise us, for, agreeable to the theory of absorption, we have to account for it only to suppose that some of the absorbent vessels are situated anterior to the hymen--a supposition by no means unreasonable.

There are two peculiarities of the human species respecting conception which I will notice. First, unlike other animals they are liable, and for what has been proved to the contrary, equally liable--to conceive at all seasons of the year. Second, a woman rarely, if ever, conceives until after having several s.e.xual connections; nor does one connection in fifty cause conception in the matrimonial state, where the husband and wife live together uninterruptedly. Public women rarely conceive, owing probably to a weakened state of the genital system, induced by too frequent and promiscuous intercourse.

It is universally agreed, that some time after a fruitful connection, a vesicle (two in case of twins) of one or the other ovary becomes so enlarged that it bursts forth from the ovary and takes the name of ovum, which is taken up, or rather received, as it bursts forth, by the fimbriated extremity of the Fallopian tube, and is then conducted along the tube into the uterus, to the inner surface of which it attaches itself.*

* Since Dr. Knowlton's work was written, the very important fact has been discovered that ova are periodically discharged from the ovaries in the human female and other animals, not in consequence of fruitful connection having taken place, as was formerly believed, but quite independently of intercourse with the male. Such a discharge of ova occurs in the lower animals at the time of heat or rut, and in women during menstruation. At each menstrual period, a Graafian vesicle becomes enlarged, bursts, and lets the ovum which it contains escape into the Fallopian tube, along which it pa.s.ses to the uterus. "It has long been known," says Dr. Kirke, "that in the so-called oviparous animals, the separation of ova from the ovary may take place independently of impregnation by the male, or even of s.e.xual union. And it is now established that a like maturation and discharge of ova, independently of coition, occurs in Mammalia, the periods at which the matured ova are separated from the ovaries and received into the Fallopian tubes being indicated in the lower Mammalia by the phenomena of _heat_ or _rut_; in the human female by the phenomena of _menstruation_. s.e.xual desire manifests itself in the human female to a greater degree at these periods, and in the female of mammiferous animals at no other time. If the union of the s.e.xes takes place, the ovum may be fecundated, and if no union occur, it perishes. From what has been said it may therefore be concluded that the two states, heat and menstruation, are a.n.a.logous, and that the essential accompaniment of both is the maturation and extrusion of ova."--"Handbook of Physiology," page 724.--G. R.

Here it becomes developed into a full grown foetus, and is brought forth about forty-two weeks from the time of conception by a process termed parturition. But one grand question is, how the s.e.m.e.n operates itself, or any part thereof reaches the ovary, and if so, in what way it is conveyed to them. It was long the opinion that the s.e.m.e.n was ejected into the uterus in the act of coition, and that it afterward, by some unknown means, found its way into and along the Fallopian tubes to the ovary. But there are several facts which weigh heavily against this opinion, and some that entirely forbid it. In the first place, there are several well attested instances in which impregnation took place while the hymen remained entire, where the v.a.g.i.n.a terminated in the r.e.c.t.u.m, where it was so contracted by a cicatrix as not to admit the p.e.n.i.s. In all these cases the s.e.m.e.n could not have been lodged anywhere near the mouth of the uterus, much less ejected into it. Secondly, it has followed a connection where from some defect in the male organs, as the urethra terminating some inches behind the end of the p.e.n.i.s, and it is clear that the s.e.m.e.n could not have been injected into the uterus, nor even near its mouth. Third, the neck of the unimpregnated uterus is so narrow as merely to admit a probe, and is filled with a thick tenacious fluid, which seemingly could not be forced away by any force which the male organ possesses of ejecting the s.e.m.e.n, even if the mouth of the male urethra were in opposition with that of the uterus. But fourth, the mouth of the uterus is by no means fixed. By various causes it is made to a.s.sume various situations, and probably the mouth of the urethra rarely comes in contact with it.

Fifth. "The tenacity of the male s.e.m.e.n is such as renders its pa.s.sage through the small aperture in the neck of the uterus impossible, even by a power of force much superior to that which we may rationally suppose to reside in the male organs of generation."

Sixth. "Harvey and DeGraaf dissected animals at almost every period after coition for the express purpose of discovering the s.e.m.e.n, but were never able to detect the smallest vestige of it in the uterus in any one instance."*

* Dewees' Essay on Superfoetation.--Author's note.

Aware of the insurmountable objection to this view of the manner in which the s.e.m.e.n reaches the ovary, it has been supposed by some physiologists that the s.e.m.e.n is absorbed from the v.a.g.i.n.a into the great circulating system, where it is mixed, of course, with the blood, and goes the whole round of the circulation subject to the influence of those causes which produce great changes in the latter fluid.

To this hypothesis it may be objected, that while there is no direct evidence in support of it, it is exceedingly unreasonable, inasmuch as we can scarcely believe that the s.e.m.e.n can go the whole round of circulation, and then find its way to the ovary in such a pure unaltered state as the experiments of Spallanzani prove it must be in, that it may impregnate.

A third set of theorists have maintained that an imperceptible something, which they have called _aura seminalis_, pa.s.ses from the s.e.m.e.n lodged in the v.a.g.i.n.a to the ovary, and excites those actions which are essential to the development of an ovum. Others, again, have told us that it is all done by sympathy. That neither the s.e.m.e.n nor any volatile part of it finds its way to the ovary; but that the s.e.m.e.n excites the parts with which it is in contact in a peculiar manner, and by the law of animal economy, termed sympathy, or consent of parts, a peculiar action commences in the ovary, by which an ovum is developed.

To both these conjectures it may be objected that they have no other foundation but the supposed necessity of adopting them, to account for the effect of impregnation; and, further, they "make no provision for the formation of mules; for the peculiarities of, and likeness to, parents, and for the propagation of predisposition to disease, from parent to child; for the production of mulattoes," etc.

A fifth, and to me far more satisfactory view of the subject than any other, is that advanced by our distinguished countryman, Dr. Dewees, of Philadelphia. It appears to harmonize with all known facts relating to the conception and something from a.n.a.logy may also be drawn in its favor. It is this, that there is a set of absorbent vessels, leading directly from the inner surface of the _l.a.b.i.a externa_ and the v.a.g.i.n.a, to the ovaries, the whole office of which vessels is to absorb the s.e.m.e.n and convey it to the ovaries.* I do not know that these vessels have yet been fully discovered, but in a note on the sixteenth page of his "Essays on Various Subjects," the doctor says: "The existence of these vessels is now rendered almost certain, as Dr. Gartner, of Copenhagen, has discovered a duct leading from the ovary to the v.a.g.i.n.a."

* This view is not held at the present day. The commonly received doctrine now is that the seminal fluid enters the uterus, whether during the intercourse or after it, and pa.s.ses along the Fallopian tubes to the ovaries; and that fecundation takes place at some point of this course, most frequently in the tubes, but also at times in the ovary itself, or even, perhaps, in the uterus. It is essentially necessary for fecundation that the spermatozoa should come into actual contact with the ovum. "That the spermatozoa make their way toward the ovarium, and fecundate the ovum either before it entirely quits the ovisac or very shortly afterward," says Dr. Carpenter, "appears to be the general rule in regard to the Mammalia; and their power of movement must obviously be both vigorous and long continued to enable them to traverse so great an extent of mucous membrane, especially when it is remembered that they ascend in opposition to the direction of the ciliary movement of the epithelial cells and to the downward peristaltic action of the Fallopian tubes. * * * There can be no doubt that it is the contact of the spermatozoa with the ovum, and in the changes which occur as the immediate consequence of that contact, that the act of fecundation essentially consists."

--"Principles of Human Physiology," 8th ed., p. 961,1876.--G.R.

Another question of considerable moment relating to generation is from which parent are the first rudiments of the foetus derived.

The earliest hypothesis with which we are acquainted, and which has received the support of some of the most eminent of the moderns, ascribes the original formation of the foetus to the combination of particles of matter derived from each of the parents. This hypothesis naturally presents itself to the mind as the obvious method of explaining the necessity for the cooperation of the two s.e.xes, and the resemblance in external form, and even in mind and character, which the offspring often bears to the male parent. "The princ.i.p.al objections,"

says Bostock, "to his hypothesis, independent of the want of any direct proof of a female seminal fluid, are of two descriptions, those which depend upon the supposed impossibility of unorganized matter forming an organized being, and those which are derived from observations and experiments of Haller and Spallanzani, which they brought forward in support of their theory of pre-existent germs."

In relation to these objections I remark, first those whose experience has been with hale females, I suspect, can have no doubt but that the female organism increases like that of the male, until an emission of fluid of some kind or other takes place. But whether this secretion may properly be called s.e.m.e.n, whether any part of it unites with the male s.e.m.e.n in forming the rudiments of the foetus, is another question. For my part I am inclined to the opinion that it does not.* I rather regard it as the result of exalted excitation, a.n.a.logous to the increased secretion of other organs from increased stimulation; and if it may be for any object or use, as it probably is, it is that of affording nature a means of relieving herself; or, in other words, of quieting the venereal pa.s.sion. If this pa.s.sion, being once roused, could not by some means or other be calmed, it would command by far too great a portion of our thoughts, and with many const.i.tutions the individuals, whether male or female, could not conduct themselves with due decorum. One fact which leads me to think that the female secretion in the act of coition is not essential to impregnation is, that many females have conceived, if their unbiased testimony may be relied on, when they experienced no pleasure.

In these cases it is more than probable that there was no o.r.g.a.s.m, nor any secretion or emission of fluid on the part of the female.

* With regard to this secretion in the female, which has nothing of a seminal character, Dr. Carpenter observes: "Its admixture with the male s.e.m.e.n has been supposed to have some connection with impregnation; but no proof whatever has been given that any such admixture is necessary."--"Human Physiology," p. 991.--G. R.

As to the objection of the supposed impossibility of unorganized matter forming an organized being, I do not believe such a thing takes place, even if we admit that "the original formation of the foetus is a combination of particles of matter derived from each of the parents."

What do, or rather what ought we to mean by organized matter? Not, surely, that it exhibits some obvious physical structure, unlike what is to be found in inorganic matter, but that it exhibits phenomena, and of course may be said to possess properties unlike any kind of inorganic matter. Matter unites with matter in three ways, mechanically, chemically and organically, and each mode of union gives rise to properties peculiar to itself. When matter unites organically, the substance or being so formed exhibits some phenomena essentially different from what inorganic bodies exhibit. It is on this account that we ascribe to organic bodies certain properties, which we call physiological properties, such as contractility, sensibility, life, etc.

When, from any cause, these bodies have undergone such a change that they no longer exhibit the phenomena peculiar to them, they are said to have lost these properties, and to be dead. A substance need not possess all the physiological properties of an animal of the higher orders to ent.i.tle it to the name of an organized or living substance, nor need it possess the physical property of solidity. The blood, as well as many of the secretions, does several things, exhibits several phenomena, which no mechanical or mere chemical combinations of matter do exhibit. We must therefore ascribe to it certain physiological properties, and regard it as an organized, a living fluid, as was contended by the celebrated John Hunter. So with respect to the s.e.m.e.n, it certainly possesses physiological properties, one in particular peculiar to itself, namely, the property of impregnating the female; and upon no sound principle can it be regarded in any other light than as an organized, and of course a living fluid. And if the female secretion or any part of it unite with the male secretion in the formation of the rudiments or the foetus in a different manner than any other substance would, then it certainly has the property of doing so, whether we give this property a name or not; and a regard to the soundest principles of physiology compels us to cla.s.s this property with the physiological or vital, and of course to regard this secretion as an organized and living fluid So, then, unorganized matter does not form an organized being, admitting the hypothesis before us as correct.

That organized being should give rise to other organized beings under favorable circ.u.mstances as to nourishment, warmth, etc., is no more wonderful than that fire should give rise to fire when air and fuel are present. To be sure, there are some minute steps in the processes which are not fully known to us; still, if they ever should be known, we should unquestionably see that there is a natural cause for every one of them; and that they are all consonant with certain laws of the animal economy. We should see no necessity of attempting to explain the process of generation by bringing to our aid, or rather to the darkening of the subject, any imaginary principle, as the _visus formaticus_ of Blumenbach.

As to the "observations and experiments of Haller and Spallanzani," I think, with Dr. Bostock, that they weigh but little, if any, against the theory before us. I shall not be at the labor of bringing them forward and showing their futility as objections to this theory, for I am far from insisting on the correctness of it; that is, I do not insist that any part of the female secretion, during coition, unites with the male s.e.m.e.n in the formation of the rudiments of the foetus.

The second hypothesis or theory, I shall notice, as to the rudiments of the foetus, is that of Leeuwenhoek, who regarded the seminal animalculse of the male s.e.m.e.n as the proper rudiments of the foetus, and thought that the office of the female is to afford them a suitable receptacle where they may be supported and nourished until they are able to exist by the exercise of their own functions. This is essentially the view of the subject which I intend to give more particularly presently.

I know of no serious objections to this hypothesis, nothing but the "extreme improbability," as its opponents say, "that these animalculae should be the rudiments of being so totally dissimilar to them." But I wish to know if there is more difference between a foetus and a seminal animalcule than there is between a foetus and a few material particles in some other form than that of such animalcule?

The third hypothesis, or that of pre-existing germs, proceeded upon a precisely opposite view of the subject to that of Leeuwenhoek, namely, that the foetus is properly the production of the female; that it exists previous to the s.e.xual congress, with all its organs, in some parts of the uterine system; and that it receives no proper addition from the male, but that the seminal fluid acts merely by exciting the powers of the foetus, or endowing it with vitality.

It is not known who first proposed this hypothesis; but strange as it may appear, it has had the support of such names as Bonnet, Haller and Spallanzani, and met with a favorable reception in the middle of the last century. Agreeable to this hypothesis, our common mother, Eve, contained a number of homuncules (little men) one within another, like a nest of boxes, and all within her ovaries, equal to all the number of births that have ever been, or ever will be, not to reckon abortions.

Were I to bring forward all the facts and arguments that have been advanced in support of this idea, it seems to me I should fail to convince sound minds of its correctness; as to arguments against it, they surely seem uncalled for. Having now presented several hypotheses of generation, some as to the manner in which the s.e.m.e.n reaches or influences the ovary, and others as to the rudiments of the foetus, I shall now bring together those views which, upon the whole, appear to me the most satisfactory.

I believe, with Dr. Dewees, that a set of absorbent vessels extend from the innermost surface of the _l.a.b.i.a externa_, and from the v.a.g.i.n.a to the ovary, the whole office of which is to take up the s.e.m.e.n or some part thereof, and convey it to the ovary. I believe, with Leeuwenhoek, that the seminal animalculae are the proper rudiments of the foetus, and are perhaps of different s.e.xes; that in cases of impregnation one of them is carried not only to, but into a vesicle of an ovary, which is in a condition to receive and be duly affected by it.* It is here surrounded by the alb.u.minous fluid which the vesicle contains. This fluid being somewhat changed in its qualities by its new-comer, stimulates the minute vessels of the parts which surround it, and thus causes more of this fluid to be formed; and while it affords the animalcule material for its development, it puts the delicate membrane of the ovary which retains it in its place upon the stretch, and finally bursts forth surrounded probably by an exceedingly delicate membrane of its own. This membrane, with the alb.u.minous fluid it contains and the animalcule in the center of it, const.i.tutes the ovum or egg. It is received by the fimbriated extremity of the Fallopian tube, which by this time has grasped the ovary, and is by this tube slowly conveyed into the uterus, to the inner surface of which it attaches itself, through the medium of the membrane, which is formed by the uterus itself in the interim between impregnation and the arriving of the ovum in the way I have just mentioned.

* The opinion that the spermatozoa of seminal filaments are real animalculae is now abandoned, but it is held by Dr.

Carpenter and other authorities that they actually, as here stated, penetrate into the interior of the ovum. "The nature of impregnation," says Dr. Hermann, "is as yet unknown. In all probability it is, above all, essential, in order that it should occur, that one or more spermatozoa should penetrate the ovum. At any rate, spermatozoa have been found within the fecundated eggs of the most diverse species of animals."--Elements of "Human Physiology," translated from the 5th ed., by Dr. Gamgee, p. 534, 1875.--G. R.

The idea that a seminal animalcule enters an ovum while it remains in the ovary, was never before advanced to my knowledge; hence I consider it inc.u.mbent upon me to advance some reason for the opinion.

First, it is admitted on all hands that the seminal animalculae are essential to impregnation, since "they cannot be detected when either from age or disease the animal is rendered sterile."

Second, the ovum is impregnated while it remains in the ovary. True, those who never met with Dr. Dewees' theory, and who, consequently, have adopted the idea that the s.e.m.e.n is ejected into the uterus, as the least improbable of any with which they were acquainted, have found it very difficult to dispose of the fact that the ovum is impregnated in the ovary, and have consequently presumed this is not generally the case.

They admit it is certainly so sometimes, and that it is difficult to reject the conclusion that it is always so. Dr. Bostock--who, doubtless, had not met with Dewees' theory at the time he wrote, and who admits it impossible to conceive how the s.e.m.e.n can find its way along the Fallopian tubes, how it can find its way toward the ovary, farther, at most, than into the uterus, and, consequently, cannot see how the ovum can be impregnated into the ovary--says, "Perhaps the most rational supposition may be that the ovum is transmitted to the uterus in the unimpregnated state; but there are certain facts which seem almost incompatible with this idea, especially the cases which not infrequently occur of perfect foetuses having been found in the tubes, or where they escaped them into the cavity of the abdomen. Hence it is demonstrated the ovum is occasionally impregnated in the tubes (why did he not say ovaria?), and we can scarcely resist the conclusion that it must always be the case."..."Haller discusses this hypothesis (Bostock's 'most natural supposition, perhaps') and decides against it."..."The experiments of Cruikshank, which were very numerous, and appear to have been made with the requisite degree of skill and correctness, led to the conclusion that the rudiment of the young animal is perfected in the ovarium."... "A case is detailed by Dr. Granville, of a foetus which appears to have been lodged in the body of the ovarium itself, and is considered by its author as a proof that conception always takes place in this organ."

The above quotations are from the third volume of Bostock's Physiology.

Now, as the seminal animalculae are essential to impregnation, and as the ovum is impregnated in the ovarium, what more probable conjecture can we form than that an animalcule, as the real proper rudiment of the foetus, enters the ovum, where, being surrounded with alb.u.minous fluid with which it is nourished, it gradually becomes developed? It may be noticed that Leeuwenhoek estimates that ten thousand animalculae of the human s.e.m.e.n may exist in a s.p.a.ce not larger than a grain of sand. There can, therefore, be no difficulty in admitting that they may find their way along exceedingly minute vessels from the v.a.g.i.n.a, not only to, but into the ovum while situated in the ovarium.

I think no one can be disposed to maintain that the animalculae merely reaches the surface of the ovum and thus impregnates it. But possibly some may contend that its sole office is to stimulate the ovum, and in this way set going that train of actions which are essential to impregnation. But there is no evidence in favor of this last idea, and certainly it does not so well harmonize with the fact that the offspring generally partakes more or less of the character of its male parent. As Dr. Dewees says of the doctrine of sympathy, "It makes no provision for the formation of mules; for the peculiarities of and likeness of parents; and for the propagation of predisposition to disease from parent to child; for the production of mulattoes," etc.

Considering it important to do away with the popular and mischievous error that the s.e.m.e.n must enter the uterus to effect impregnation, I shall, in addition to what has been already advanced, here notice the experiments of Dr. Haighton. He divided the Fallopian tubes in numerous instances, and that after the operation a foetus is never produced, but that _corpora lutea_ were formed. The obvious conclusions from these facts are that the s.e.m.e.n does not traverse the Fallopian tubes to reach the ovaria; yet, that the ovum becomes impregnated while in the ovarium and, consequently, that the s.e.m.e.n reaches the ovum in some way, except by the uterus and Fallopian tubes. I may remark, however, that a _corpus luteum_ is not positive proof that impregnation at some time or other has taken place; yet they are so rarely found in virgins that they were regarded as such proofs until the time of Blumenbach, a writer of the present century.*

* A _corpus luteum_ is a little yellowish body, formed in the ovary by changes that take place in the Graafian vesicle after it has burst and discharged its contents. _Corpora lutea_ were formerly considered a sure sign of impregnation, as they were thought to be developed only or chiefly in cases of pregnancy, but it is now known that they occur in all cases where a vesicle has been ruptured and an ovum discharged; though they attain a larger, size and are longer visible in the ovary when pregnancy takes place than when it does not.--G. R.

"Harvey and DeGraaf dissected animals at most every period after coition for the express purpose of discovering the s.e.m.e.n, but were never able to detect the smallest vestige of it in the uterus in any one instance."--Dewells Essay on Superfoetation. The fact of superfoetation furnishes a very strong argument against the idea that the s.e.m.e.n enters the uterus in impregnation.

A woman being impregnated while she is already impregnated const.i.tutes superfoetation. It is established beyond a doubt that such instances have occurred, yet those who have supposed that it is necessary for the s.e.m.e.n to pa.s.s through the mouth of the uterus to produce conception have urged that superfoetation could not take place, because, say they--and they say correctly--"so soon as impregnation shall have taken place, the _os uteri_ closes and becomes impervious to the s.e.m.e.n ejected in subsequent acts of coition."

Dr. Dewees related two cases, evidently cases of superfoetation, that occurred to his own personal knowledge. The first shows that, agreeable to the old theory, the s.e.m.e.n must have met with other difficulties than a closed month of the uterus,--it must have pa.s.sed through several membranes, as well as the waters surrounding the foetus, to have reached even the uterine extremity of a Fallopian tube. The second case I will give in his own words:

"A white woman, servant to Mr. H., of Abington township, Montgomery county, was delivered about five and twenty years since of twins, one of which was perfectly white, the other perfectly black. When I resided in that neighborhood I was in the habit of seeing them almost daily and also had frequent conversations with Mrs. H. respecting them. She was present at their birth, so that no possible deception could have been practiced respecting them. The white girl is delicate, fair-skinned, light-haired and blue eyed, and is said very much to resemble the mother. The other has all the characteristic marks of the African; short of stature, flat, broad-nosed, thick-lipped, woolly-headed, flat-footed, and projecting heels; she is said to resemble a negro they had on the farm, but with whom the woman would never acknowledge an intimacy; but of this there was no doubt, as both he and the white man, with whom her connection was detected, ran from the neighborhood as soon as it was known the girl was with child."

I am aware that some have thought that they had actually discovered s.e.m.e.n in the uterus, while Ruysch, an anatomist of considerable eminence, who flourished at the close of the seventeenth century, a.s.serted in the most unequivocal manner that he found the s.e.m.e.n in its gross white state in one of the Fallopian tubes of a woman, who died very soon after, or during the act of coition; but says Dewees, "the s.e.m.e.n, after it has escaped from the p.e.n.i.s, quickly loses its alb.u.minous appearance and becomes as thin and transparent as water. And we are certain that Ruysch was mistaken. Some alteration in the natural secretion of the parts was mistaken for s.e.m.e.n. This was nowise difficult for him to do, as he had a particular theory to support, and more especially as this supposed discovery made so much for it. It is not merely speculative when we say that some change in the natural secretion of the parts may be mistaken for s.e.m.e.n, for we have the testimony of Morgani on our side. He tells us he has seen similar appearances in several instances in virgins and others, who have been subject during their lives to leucorrhae, and that it has been mistaken by some for male s.e.m.e.n."

On the whole I would say, that in some instances, where the mouth of the uterus is uncommonly relaxed, the s.e.m.e.n may, as it were, accidentally have found its way into it; but that is not generally the case, nor is it essential to impregnation; and further, that whatever s.e.m.e.n may at any time be lodged in the uterus, has nothing to do with conception. It is not consistent with a.n.a.logy to suppose that the uterus has vessels for absorbing the s.e.m.e.n and conveying it to the ovaria, considering the other important functions which we know it performs.

The circ.u.mstances under which a female is most likely to conceive are, first, when she is in health; second, between the ages of twenty-six and thirty; third, after she has for a season been deprived of those intercourses she had previously enjoyed; fourth, soon after menstruating. Respect-ing this latter circ.u.mstance, Dr. Dewees remarks, "Perhaps it is not erring greatly to say, that the woman is liable to conceive at any part of the menstrual interval. It is generally supposed, however, that the most favorable instant is immediately after the catamenia have ceased." Perhaps this is so as a general rule, but it is certainly liable to exceptions,* and he relates the following case which occurred to his own notice:

* This view, which concerns a question of the utmost practical importance, is held at the present day by the great physiologists. It is believed that although conception may occur at other times, it is much more likely to happen from intercourse a few days before or after the menstrual periods; that is to say, during the time when ova are in process of being ripened and detached from the ovaries, and before they perish and are conveyed out of the body. "There is good reason to believe," says Dr. Carpenter, "that in the human female the s.e.xual feeling becomes stronger at the period of menstruation; and it is quite certain that there is a greater apt.i.tude for conception immediately before and after that epoch, than there is at any immediate period.

This question has been made the subject of special inquiry by M. Raciborski, who affirms that the exceptions to the rule--that conception occurs immediately before or after or during menstruation--are not more than six or seven per cent. Indeed, in his latest work on the subject, he gives the details of fifteen cases, in which the date of conception could be accurately fixed, and the time of the last appearance of the catamenia was also known, and in all but one of them the correspondence between the periods was very close."--"Human Physiology," p. 959. So, too, Dr.