cord passing downward. Between the cerebellum and the medulla is the fourth ventricle. In front of the spinal cord are sections of the bodies of the vertebræ; the white intervertebral substance may be seen between them. In the upper portion of this section of the face may be seen the right frontal sinus, with the crista galli just posterior to it, below this is the right nasal fossa with its turbinate bones and its meati. Posterior to the upper portion is the sphenoidal sinus.

Back of the lower portion is the posterior nares, where the nasal fossa opens into the upper portion of the pharynx. The floor of the nasal fossa extends from the anterior nares backward in a dome or convex-shape and terminates close to the postpharyngeal wall, leaving but a small opening in the median line. The incisor teeth are in about normal occlusion. The longitudinal section of the tongue and its radiating fibres are beautifully shown. The fibres commence principally from the genial tubercles, the upper fibres are the genio

glossus, while the lower ones are the geniohyoglossus. At the base of the tongue is a transverse section of the hyoid bone. The epiglottis is well shown passing from the base of the tongue upward and backward until it nearly reaches the postpharyngeal wall. Below this is the larynx.

The Tongue.-Gray, Allen and other leading anatomists describe the tongue as being "situated in the floor of the mouth in the interval between the lateral portions of the body of the jaw." It is evident that they did their dissecting upon somewhat dried subjects, similar to that shown in Fig. 1, and when they examined the living subject it was naturally with the mouth open, and consequently the hyoid bone and all associated with it were drawn downward.. When the mouth is closed in the normal living subject the tongue almost completely fills the space from the floor of the mouth to its roof, from the anterior teeth to nearly the postpharyngeal wall, and from the premolar and molar teeth on one side to those of the other, so much so that the sides of the tongue arè more or less indented by pressure against the teeth, and the buccal surface of the cheeks is in somewhat the same condition, though when the mouth is thrown wide open those indentures are usually lost. If a tooth be lost the tongue will pass outward into the space that it occupied, while the cheek will pass inward endeavoring to meet the tongue. See Figs. 2, 3, 4 and 5. It is due to this cause that a space feels so large to the tongue when a tooth has been extracted, as it does not come in contact with the usual resistance when an artificial tooth replaces it, the tongue and cheek having nearly or quite met through the open space. See Fig. 5. The tooth feels large and uncomfortable, but in a short time the tongue becomes accustomed to the new tooth, or in other words, the soft tissues recede into the same position as before extraction.

It would be natural to suppose that the tongue, being so large and pressing outward, would have more or less influence in moulding the shape of the alveolar arches, but from observing various bilateral sections of the face shown in Figs. 3, 4 and 5 I would claim that the mouth has more to do in shaping the tongue than the tongue has in shaping the mouth. In Figs. 2 and 8 it will be noticed that the outer surfaces of the tongue are smooth and conform to the surfaces of the mouth, alveolar processes, and the teeth, while in Fig. 3, from a slightly narrowed skull, the tongue is somewhat compressed and

is irregular in its outline. In Fig. 4, from a much narrowed skull, the tongue is very much compressed and is quite irregular in its outline.

In Fig. 8 the epiglottis will be noticed at the posterior base of the tongue passing upward and backward. In discussing Dr. Roe's

paper, the sudden collapse of his patient was thought by some to be due to the tongue falling backward, which caused the epiglottis to close over the glottis. This I thought was partly a mistake, as I do not believe that the epiglottis acts as a lid to the glottis. It is more of a stationary organ, and its nearest relation to the glottis is when the larynx is raised toward it, and even at that time the epiglottis is carried upward with the base of the tongue and the hyoid bone. Some years ago I made a number of experiments upon several cats and dogs. After placing them under an anesthetic I

opened the tissue covering the region of the glottis and epiglottis in order to obtain a general view of the parts, allowing the teeth to remain in occlusion. By passing water into the posterior parts of the mouth with a syringe deglutition was forced. The water passed backward and downward, and in the act of deglutition the folds of the glottis would close the opening, but no special movement of the

epiglottis could be observed, even when water was injected between the folds of the glottis. The epiglottis has sometimes been lost in man by disease and traumatism without interfering with the functions of the glottis, and in many of the lower animals no epiglottis exists at or near the glottis at the base of the tongue, showing that it is not necessary for this organ to protect the glottis. I have removed the organ from several cats and allowed the parts to heal over, with no apparent difference in the deglutition or breathing. As the epiglottis is a concavo-convex organ, with the convex portion toward the mouth, it will act as a shield to the glottis and cause the

fluids to go to the right and left as they pass the partly raised tissue surrounding it.

During the surgical operation for removing the condyles of the mandible, the principal reason for the patient's failing to breathe properly was, that this operation allowed the lower jaw, the hyoid bone, the tongue and all the surrounding tissues of that region to

fall backward against the postpharyngeal wall, closing the pharynx, and thus shutting off the air before it can reach the glottis.

The roof of the typical mouth before the loss of the teeth and alveolar process is dome-shaped, both transversely and antero-posteriorly, and extends nearly from the anterior teeth backward to the postpharyngeal wall. See Figs. 2, 3, 4 and 8. During deglutition it extends completely to the postpharyngeal wall. The wall advances slightly to meet the uvula and the free edge of the soft palate.