The malformation of the bones of the skull and of the face is very great; but as its de scription would take too much room here, I refer the reader to my handbook and my plates, and also to fig. 607., which will give a clear idea of it.
lumn is either perfect, or partially, and some times entirely, cleft. The last of these con ditions is represented in fig. 608.
To this form of monstrosity Geoffroy St. Hilaire gives the name of anencephalus. Spe cimens of it were found amongst the Egyptian mummies in the sacred sepulchres of the Cy nocephali and Ibis, which is a very interesting fact as regards monstrous births in those times.
Third Type. — The surface of the basis cranii only partially denuded, — a spongy tumour occupying the place of the brain. The skull may be closed at its posterior part, and remain open at its summit. A more or less malformed cerebral substance appears on the summit of the skull, just as if it were Second Type.— The denuded surface of the basis cranii occupied by a spongy substance, instead of brain. — In most eases vesicles, filled with a serous liquor, were observed to occur in this spongy substance, and with these occasionally also medullary corpuscles, which may be considered as rudiments of brain. There is sometimes a rudiment of the cerebellum, together with a rudiment which is continued into the spinal medulla, as though it were a medulla oblongata. The cerebral nerves are sometimes quite separated from, sometimes united with, the spongy substance. Sometimes they have the form of complete or lacerated bags, which extend along the superior surface of the skull and the posterior surface of the spinal column. The spinal co a hernia. The parietal bones are sometimes present, together with flat frontal bones, and a perpendicular occipital bone, so that the summit of the skull is quite closed, with the exception of a small opening. Fig. 609. shows how the malformed cerebral substance is applied to the medulla spinalis. All the cerebral nerves are present.
This form of monstrosity has in general a less brute-like aspect ; the trunk is more evolved, and the whole body in general very heavy.
Fourth Type.—The skull fiat, more evolved, but having an opening, through which the brain protrudes as a hernia.—This is what we call a cerebral hernia (hernia cerebri, encephalocele), viz. a tumour covered with the external integu ments arising from some part of the surface of the skull, and containing a part of the brain. It has commonly the form of a bag, appended to the posterior part of the skull, and resting on the neck. The head is never turned with the face upwards ; the ears do not rest on the shoulders ; the neck is not wanting. The summit of the skull is flat and closed, and its cavity is too small to include the brain, which for this reason is placed on its outside, and backwards. The occipital bone has the form of a vertebral arc, which surrounds the brain, lying at the outside. Fig. 610. shows the external appearance of In many of the published observations, a collection of serous fluid accompanied the hernia cerebri, by which a hydro-encephalocele was formed.
The situation of the cerebral hernia is in general on the occiput, but sometimes on both sides of the root of the nose (W. Lyon, Kelch) • above the eye (Adams); on the forehead (Beclard, Saxtorph, Niemeyen, Bredon, Guyenot); on the fontanella magna (Held) ; in the parietal bone (Le Dran, Stein, Tren) ; on the glabella, between the orbits (Otto).
On a survey of these various types, it ap pears that they all belong to the same class of monstrosities. The nature of the malform ation is in all the same, namely a defective de velopement of the skull and of the brain. This takes place in different degrees, so as to convey us gradually from the complete want of brain to those cases in which it is nearly perfect, and differing from the natural condition only in situation. The constancy of form is very interesting in this monstrosity, so that the malformed children resemble each other nearly in every museum, and the pub lished observations are quite accordant with the cases now occasionally occurring. This proves that the origin of the malformation cannot be accidental. The want of the neck, which is the reason why the ears rest on the shoulders and the chin on the breast, and which gives to this form of monstrosity such a pecu liar character, is often the consequence of the want of some of the cervical vertebrm (Rathke, Haller, Otto), or of their mutual coalition (Rathke, W. Vrolik), or of their shortness (Sandifort.) As a transition to the brute form, this shortness of the neck is interest ing, reminding us of the condition of the Cetacea. The prominence of the eyes is oc casioned by the flatness of the orbits, and by the backward direction of their superior margin. It differs from the manner in which the eyes are prominent in children with internal hydrocephalus. A rich growth of hair is common to all the forms of acrania. Is not this, and likewise the abundance of areolar tissue, to be attributed to a vicarious nutritive function ? The frequent absence of the suprarenal glands (Otto), or at least their imperfection and smallness (Morgagni, Hewson, F. Meckel, Soemmering, W. Vrolik) in all acranial fcetuses is remarkable. The capacity for persistent life after birth differs according to the different forms of this monstrosity. Acrania does not seem to in terfere with uterine life. The children who are affected with it are all well nourished, and some of them even very large, at the moment of their birth. Nevertheless, they rarely live longer than a few hours. During this short life they offer some symptoms which are attributable to the reflex action of the nervous system ; such as, for instance, mus cular contractions when the skin is touched, rejection by the mouth of the recently ex pressed juice of Pelargonium and the attempt to suck a finger introduced the mouth. In cerebral hernia the chance for the prolongation of life is greater. Some cases are known in which life lasted 20, SO, and even 60 years. When complicated with hydrocephalus, puncture has sometimes been instituted, but without success (Earle). Extirpation produced, in another case, in stantaneous death.