c. Single hare-lip. — This name is adopted for the malformation when it is limited to one lateral part of the face. It may be complicated with fissured palate. The lip is then, on one side, fissured to the nostril, so as to form there an immediate communication between the oral and nasal cavity. The direction of the fissure is seldom accurately in the mesial line. If this occurs, it is the result of defective in termaxillary bones. The palate offers either a simple or a double fissure. In a less degree of malformation only the alveolar ridge is cleft, and, in the least, the palate is complete. In such a case the fissure of the upper lip is merely a small incision.
d. Fissure of the palate without a hare-lip. — The alveolar margin is in this case quite complete, but the palatine and the supermaxil Lary bones are largely separated from each other posteriorly, so as to form a fissure, more or less extensive, of the bony and of the soft palate. Sometimes there is only a fissure of the uvula (Von Ammon). The nearest ap proach to the natural state is, when the planes of the palatine bones' form with each other an acute angle rising high upwards in the nasal -cavity (Himly, W. Vrolik). In some cases, the palate is fissured at its anterior part, close to the foramen palatinum anticum (hiatus fora minis palatini antici, Von Ammon). En re sume, it appears that fissure of the palate and hare-lip are independent of each other. But it may happen that, originally, the fissure of the palate coexists with the hare-lip and closes itself later. The indentation which is ob served in harelip without fissure of the palate, .between the external incisive and the canine tooth, makes it probable that nature proceeds in this manner. It is also not improbable that hare-lip may sometimes be cured spontane ously in the womb. The gradual transition of the various forms of this malformation into each other, shows that its cause is not external and accidental, and that it is produced, neither by blows which the child inflicts upon itself with its fists (Jourdain), nor by a mechanical im pediment preventing the union of the palatine lamina: (Pinnder). Complete fissure of the face and the palate is rather to be considered -as an arrest of developement at an early period of formation. Hare-lip conforms with the foetal condition in that period of develope ment which I have called the third. If the original intermediate protuberance does not -unite itself with the lateral parts, double hare lip is formed. The protuberance obvious in it is formed by the intermaxillary bone either in its totality, or only by a part of it. If it unites itself with only one lateral part, single hare-lip is formed. The intermaxillary bone is composed of four separate parts, of which each contains an alveolus. The result -of this is, that each of these parts may be united, separately, with the supermaxillary -bones ; which fact explains clearly why only three or two incisive teeth are sometimes to -be found in the protuberance. The fissure of the upper lip sometimes occupies the mesial line, passing through the middle of the inter maxillary bone. This is also the case when the
intermaxillary bone is wanting.
In this way, all the various forms of fis sure of The face can be reduced to an arrest of developement,- which explains in the mean -time the constant tendency of the fissure to close itself, as may be observed in children having this malformation. Fissure of the palate and lip does not endanger the life of children, and union of the separated parts in hare-lip and cleft palate can be obtained by a surgical operation.
e. Fissure of the under lip.— The under lip is very seldom cleft (J. F. Meckel, Von Ammon, Nicati, Bonisson). It is equally rare for the under jaw to remain after birth separated into two parts.
Many forms of this monstrosity are known, to which different names have been given, as acephalia spuria, microcephalia, anencephalia, henzicephalia. But, for its shortness and ety mological sense, I prefer the name of acrania, which was introduced by J. F. Meckel. Un der this name I comprehend all the different forms in which this malformation occurs, and also, with Himly, the hernia cerebri. Accord ing to my opinion, the division into different families and genera, and the nomenclature of J. Geoffroy St. Hilaire, ought to be rejected. I, for my part, am always inclined to simplify science as much as possible, and to be succinct in its exposition ; and I propose, therefore, the following types.
First Type. — Want of the brain, and ex posure of the whole basis of the skull. — The superior surface of the cranium is flat, and not formed by the bones of the skull, but only by a membrane, of which the margin is very un equal, hard, and formed by bones. The external integuments extend over this margin, and terminate there in an unequal line, which is distinctly circumscribed by the thick hair of the head. With this cutaneous border is connected the slightly vaulted membrane, of a red, somewhat bloody colour, which imme diately covers the periosteum that invests the more or less convex surface of the basis of the skull. The brain is wanting, but the central terminations of the cerebral nerves are in most cases present, yet sometimes these also are wanting (J. F. Meckel). The forehead is flat, and directed forwards in an oblique direction. The eyes protrude on its anterior or orbital margin, covered with swollen superior eyelids, and directed more or less upwards. The face is flat, and nearly horizontal ; the upper, and still more so the under jaw are comparatively longer than those of a well-formed subject ; the tongue is in general prominent, because the mouth cannot be shut on account of the length of the under jaw. These distortions give to such monstrosities a certain brute-like aspect which induced the Germans to call them Xatzenkopfe and the French tOtes de crapaud. If the cervical part of the spinal column is in the meantime cleft, the cervix is so shortened, that the head seems to be fixed on the shoul ders, and the chin rests on the breast, as is represented in fig. 606.