other parts of the larynx must present minute differences, as difficult, however, to characterise as those which the human countenance presents.

SPEECH

Is performed in the buccal cavity, and that the larynx is unconnected with the faculty may be proved by passing a tube through the nares to the back of the mouth; when air is forced through it while the breath is held, articulate sounds are expressed, but in whispers. If the larynx was used at the same time, vocal sounds were emitted along with the whispers. The proportional dimensions of the oral aperture and buccal cavity give rise, in a great measure, to the different vowel sounds, as shown by the following table:

The diphthongs are produced by the transition of these states in producing two pure vowel sounds.

Consonants are divided into explosive or sudden, including b, p, d, t, g, k, and continuous, namely, v, f, 1, m, n, r, s, z, and also the sounds th and sh, which, though written in many languages with two letters, are really simple sounds. The division into labial, dental, lingual, palatal, and guttural, is inaccurate and artificial.

Speaking Machines have been often attempted. It is said one constructed by Kempelen could pronounce such sentences as "Je vous aime de tout mon cœur," "Imperator Romanorum," &c.

Ventriloquism was said by Magendie to be but the imitation in the larynx of sounds produced at a distance;

by others, to be produced by using the air in inspiration instead of expiration, for vocalising; and by Müller to be performed by filling the chest so fully as to protrude the abdominal viscera, and then allowing air to escape slowly by contracting the sides only of the chest, the glottis also being kept narrow. An expert professor of the art also deceives our other senses by directing attention to some spot in the direction whence we suppose the sound to issue.

Stammering is usually no structural fault of the vocal organs, but a nervous affection-volition, and co-ordinating influence over the articulating muscles being imperfect. It is, therefore, much augmented by mental excitement and the anxiety to speak correctly which is usually evinced, and these facts suggest to us the principal curative indications.

QUESTIONS FOR EXAMINATION.

JUNIOR.

1. What constitutes the skeleton of the larynx, and what the active parts?

2. What is the action of the posterior crico-aryteniod muscles? 3. What musical instrument resembles the larynx most, and explain the analogies?

4. Can the nature of ventriloquism be explained physiologically?

SENIOR.

1. Explain the mechanism of the vocal cords, and say how they are stretched, relaxed, approximated, and separated.

2. Arrange the varieties of voice according to the rapidity of vibrations.

3. What are the organs of speech, and how has it been shown that articulation is not produced in the larynx ?

4. What are the nature and remedy of stammering?

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CRANIAL NERVES AND SPECIAL SENSES.

THE cranial nerves are 9 in number according to Willis's arrangement; whereas Sömmering, by subdividing the 7th and 8th, enumerated 12. Their functions are most varied, some being specially sensitive, others purely motor, and a third class are compound. As all of them, except the pneumogastric and spinal accessory, are in part or wholly distributed to the organs of sense, it will be best to consider them in describing these organs. They may, however, be classified according to their functions as follows:

The

The special senses, "the gateways of knowledge," are five in number-namely, touch, taste, smell, sight, and hearing; and they are termed special, as each has its proper excitant to which the others are insensible. three first require the application of ponderable agencies; light and sound are imponderable influences. Sensations are objective when an impression is made on the periphery, and conducted back by the nerve to that part of the cranio-spinal axis appropriated for its perception; subjective, when produced by some central cause.

TOUCH

We shall first describe, as it is the most generally diffused over the body, and also throughout the animal kingdom. It exists in the interior of the body, and we

become thus aware of such conditions as pain, warmth, repletion, &c.; but as it attains the highest degree of perfection on the surface, we may regard the skin as its

special organ. The an

nexed diagram represents a section of the skin, and its various parts are described in the ensuing pages.On the surface is seen the cuticle, with the deeper cells more rounded and of a darker colour than those which lie externally, the gradual transition showing that the rete mucosum, or layer between the cuticle and cutis, has no real existence. Next are seen several papilla with branching nerve filaments, and at the base they are seen to be continuous with the basement layer. The areolæ of this portion are filled with fat cells. To the left is seen a perspiratory gland and its excretory duct taking a spiral course through the cuticle. A hair is

To the left is a perspiratory tube, and in figured in its follicle, into the centre a hair in its follicle, with which is inserted one of the erectores pilorum, and two sebaceous glands, with an entozoon in each.

an erector muscle attached, and two
sebaceous glands opening into it.

The skin, like the internal integument we have before described, is divisible into 2 layers-the cuticle and cutis

vera.

The Cuticle, epidermis, or scarf-skin, is thickest in

places exposed to pressure-as the soles of feet and palms of hands-and as it follows the arrangement of the true skin, it presents furrows and other markings, in some situations, as the fingers. It is composed of cellsround, large, and moist next the cutis, and getting flatter, smaller, and drier, through successive layers, till, becoming scales, they are cast off at the surface. The deepest and newly-formed cells constitute the "rete mucosum, vel Malpighii." They are of a darker colour, being filled with pigment granules, and are black in the Negro. Scars are white, as the new cuticle and cutis adhere, the rete mucosum not being restored. The coloration due to nitrate of silver and bile has its seat in this tissue. The dark colour of races inhabiting warm countries is of use in absorbing the rays of heat, producing evaporation and consequently cold. It appears to be due originally to the carbon of the tissues not being sufficiently burned off, as the air is so rare in the warm countries which they inhabit and their diet is so carbonaceous. The sweat ducts open obliquely through the cuticle so that when serum collects under it after a blister, it does not escape.

Cuticle, as well as hair and nails, consists of keratin, a substance intermediate between the albuminoids and gelatin, and containing sulphur. The cuticular appendages are the nails and hairs. Nails and their analogues-claws and hoofs-serve for prehension or support at the extremities of the fingers and toes. The root of the nail is set upon a highly vascular and sensitive surface, the matrix, consisting of a row of papillæ, which secrete the horny tissue, and which, for this reason, often presents longitudinal streaks. Near the root there is a whitish, opaque, semilunar mark-the lunula-and in front of this, streaks corresponding to the markings of the cutis. Nails grow rapidly and in a peculiar curved or adunque form in phthisis.

Hairs grow on all parts of the skin save the palms