• fimbriæ, appears to be fitted for the reception of the ovum as well as of the semen, and the ovum is probably retained in this situation for several days, to prolong the opportunity of its being impregnated.

It has been disputed, whether the semen ever comes in contact with the ovum, or even arrives at the uterus; but as Mr. HUNTER has proved by experiment that it reaches the uterus,* and as there is no impediment to its passage from that organ to the ovarium, it must be admitted that the semen reaches the ovum before impregnation can take place.

The formation of ova in the ovaria, and their appearing in that organ in succession, joined to the circumstance of animals during the warm season being ready to receive the male once a month, leads to an opinion very contrary to that which is commonly received respecting menstruation. This discharge has been supposed a previous step, preparing the uterus for uterogestation; and if a woman has not been impregnated soon after menstruation, it is presumed that she may be more fortunate after her next period.

It is clear from the case which has been stated, that such periods are totally unconnected with the formation of the ovum, the process of its leaving the ovarium, or its impregnation; but, if impregnation does not take place, such a discharge may be necessary for the relief of parts to which there had been so great a derivation of blood, as the only means of restoring them to their natural state. The uterus in women and in the monkey has a more compact form than in other animals, which may explain the circumstance of menstruation being confined to them,

J. HUNTERUS Canis fœminæ inter coeundum occisæ, uterum aperuit; quo facto maris semen in ipsum uterum, per saltus intromissum, clare vidit.

In proof of menstruation not being necessary for imprégnation, I shall mention the following case. A young woman was married before she was seventeen, and, although she had never menstruated, became pregnant; four months after her delivery she became pregnant a second time, and four months after the second delivery she was a third time pregnant, but miscarried; after this she menstruated for the first time, and continued to do so for several periods, and again became pregnant.

I have given Mr. BAUER'S account of the ovum, and the drawings he has made of it, in his own words, than which none can be more clear or satisfactory.

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"On closely examining the subject under the microscope, I found it consisted of membrane, which, considering the extreme minuteness of the subject, is of considerable thickness and consistence, very little transparent, quite smooth, and milk white, forming a kind of bag or pouch of an irregular oval shape, not quite parts of an inch in length, and in its middle about 20 parts of an inch broad; on one side it has an elevated' ridge or large fold along the whole length, and on the opposite side it is open nearly the whole length, but has no appearance of being torn, the edges of the membrane being smoothly rolled inwards, which gives it much the shape of a little shell of the genus Voluta.

When laid on glass, the membrane admitted easily to be laid open on both sides, with the point of a fine camel hair pencil. When thus opened, I found it contained another smaller bag somewhat less than 1 parts of an inch long, and not quite parts of an inch broad, ending at the upper extremity nearly in a point, but the under extremity was very obtuse or truncate, and in the middle it was slightly

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contracted, which gave it the appearance of a young seed capsule of some plants that contain only two seed kernels.

"This inner bag consisted of a seemingly very thin, perfectly smooth, and glossy membrane, which seemed to have considerable strength, as it bore to be rubbed pretty strongly, not only with the camel hair pencil, but also with the point of the quill; it seemed to be filled with some thick slimy substance, as an impression made on it with the point of the quill remained for a considerable time visible: it contained two round corpuscules, apparently more opaque, and of a yellowish tint; they were not only visible through the transparent membrane, but they swelled the membrane over them, so that the light and shade made them to be distinctly seen; and by slightly pressing the bag with the quill between the two corpuscules, they could be separated to a greater distance from each other, but on putting more moisture upon the subject, they returned quickly to their former position. This little bag was along its whole length, with its back part strongly fixed to the outer membrane, at least I could not remove it with the camel hair pencil, and more force I was afraid to employ.

"I attempted to open the little bag, if possible, to extract the corpuscules, but on piercing, with the point of a very small needle, the upper extremity, a thick slimy matter, like honey, came out, and with the membrane adhered to the needle, so that I could no farther proceed; and fearful of spoiling the whole, I gave up the attempt, and left the subject on the glass to dry; but I observed, as the spirit and moisture gradually evaporated, so the little bag flattened, and, as if melting, shrunk into the outer membrane, and almost disap

peared, but in a strong light was still visible in the micro

scope.

"When quite dry, its colour changed to a light yellowish brown, and it lay quite loose on the glass, except at the upper extremity, where I attempted to open it; it was strongly glued to the glass, and it required several times to be moistened at that part with water, to remove it from the glass.

"I have now placed it between two pieces of talc in an ivory slider; and in a strong light the two corpuscules may still be seen through a common magnifying glass."

The drawing of the uterus (Pl. VIII.) is of the natural size : the parts are so distinct that no letters of reference appear to be necessary to point them out. The ovum is shown exactly in the spot in which it was discovered, with the appearance which it at that time put on.

The drawings of the ovaria and Fallopian tubes are magnified four times, to give a more exact notion, than could be otherwise done, of the canal through which the ovum passes, before it arrives at the cavity of the uterus. The appearance the corpora lutea put on, is the most exact representation from nature. In the right ovarium, cells remain where former ova had been formed, and one corpus luteum, which is cut through the middle, has made considerable advance in its formation, another appears to be in a much earlier stage, all the different orifices are the transverse and oblique sections of blood vessels.

In the left ovarium, the opening through which the ovum, the subject of the present Paper, passed out, is distinctly seen, and the cavity in which it was contained, is filled with coagulated blood in a laminated form; behind this, the glandular