At

toms are present, especially mental depression and sleeplessness. Anesthesia also has been said to be present in the bald areas. times there has been inequality of the pupils. The disorder generally pursues a chronic course, persisting at times for several years, and then not rarely exhibiting remissions and exacerbations. Generally the hair grows again, but often it is at first lighter and rather resembles lanugo. Nothing of a definite nature is known with regard to the etiology and the nature of circumscribed alopecia. By some observers the disorder is considered a trophoneurosis, and emphasis is placed upon the fact that it occurs in anemic and nervous persons and develops after emotional disturbances. Others

FIG. 34.-Circumscribed alopecia in the occipital region in a man 27 years old (personal observation).

attribute it to parasitic influences, laying emphasis especially upon its epidemic occurrence and infection in schools and barber-shops. The treatment consists in applications of mercuric chlorid (11000) to the head, followed by inunctions of oil (oil of mace 10.0-21 fluidrams, olive-oil 40.0-11 fluidounces).

BRITTLENESS OF THE HAIR (TRICHORRHEXIS).

Long hairs upon the head and in the beard occasionally undergo fibrillation at their extremity-so-called trichoptilosis-for the relief of which the only remedy consists in cutting the hair with scissors. Occasionally, small nodules form upon the hair of the

beard at short intervals, like the ova of pediculi, and at times also upon the eyebrows and the pubic hair-so-called nodose trichorrhexis. On traction the hairs readily break at these points. On microscopic examination it will be found that the cortical cells of the hair are fibrillated in the situation of the nodes and project into one another like hair-brushes (Fig. 35). Often such altera

FIG. 35.-Splitting of the end of a hair: T.n., trichorrhexis nodosa; S.p., scissura pilorum (Michelson).

tions probably result from too vigorous rubbing in the process of drying; whether parasitic influences are also operative has not been demonstrated.

In South America nodular formations of brownish color upon the hair have been described and designated piedra, and the cause for which has been demonstrated to be a filamentous fungus. Collections of micrococci occasionally give rise to the formation of nodules upon the hairs. At times atrophy of the medulla and the cortex of the hairs takes place in limited areas, so that the intervening healthy portions of hair present a spindleshaped enlargement, and the condition has been designated intermittent or moniliform aplasia of the hair.

ATROPHIC DISORDERS OF THE NAILS

(ONYCHOATROPHY).

Congenital atrophy of the nails occurs occasionally in conjunction with deficient development of the fingers, the toes, and the teeth. The nails may be totally wanting or be but imperfectly developed. Acquired atrophy of the nails develops in the sequence of severe diseases, such as pulmonary tuberculosis, typhoid fever, carcinoma, and diabetes. Under such conditions the nails become thin and dark-colored and they peel. Chronic diseases of the skin also (eczema, psoriasis, ichthyosis, lichen ruber) are occasionally followed by atrophy of the nails. At times white spots appear in the nails in consequence of the presence of air. Such a condition has been observed in the sequence of typhoid fever and of polyneuritis, but sometimes no cause could be demonstrated.

ATROPHY OF THE CUTIS.

Among the circumscribed atrophies of the skin are the so-called stric, which develop after marked stretching of the skin. The cicatrices of pregnancy are the best known, but striæ appear upon the abdominal walls also after peritonitis, ascites, ovarian and

other abdominal tumors. They appear upon the thighs and the buttocks in obese and edematous individuals and as a result of nervous influences. Senile atrophy of the cutis occurs at advanced age, and gives rise to thinning and wrinkling of the skin. Occasionally diffuse atrophy of the skin develops in early life. This generally begins in the lower extremities, and extends thence to the trunk and the arms. The skin becomes thin and dry and appears wrinkled like cigaret-paper. It can be readily raised in folds, and is covered with brownish and reddish spots, so that it presents a mottled appearance, as from contusions. Under such conditions all of the layers of the skin have been found atrophied. The disorder should not be confounded with relaxed skin, in the presence of which the patient is capable of lifting the skin in such enormous folds as will wholly enclose an extremity. Under these conditions mucoid transformation has been found in the cutis. The designation simple xeroderma has been applied to a form of congenital atrophy of the skin that begins in earliest childhood, and generally involves the lower extremities, much less frequently also the arms. The skin of the affected parts is thin and shiny, like gold-beaters' skin, often wrinkled and desquamating readily. It can be raised in folds only with difficulty, is exceedingly sensitive, and interferes with walking and prehension. The greatest relief is afforded by oily inunctions, in order to maintain the skin in a pliable condition. Pigmented xeroderma also generally begins in the first years of life, and occurs frequently in Jews. Occasionally it has been observed in several members of the same family. Uncovered portions of the body, especially the face, the ears, the nucha, the back, the forearms, the legs, and the feet, are first affected. Brownish and blackish spots appear upon the skin, which is thin and can be raised in folds only with difficulty. The intervening skin generally is remarkably white, but contains dilated vessels. In the course of from one to four years papillary elevations appear upon the skin, representing carcinomata, sarcomata, or angiomata. Neoplasms occasionally develop also in internal viscera. Death results in consequence of progressive exhaustion, as treatment. (arsenic, removal of the cutaneous growths with the knife) has hitherto been unsuccessful.

V. CUTANEOUS NEUROSES.

ITCHING OF THE SKIN (CUTANEOUS PRURITUS».

Symptoms, Diagnosis, and Prognosis.-The designation cutaneous pruritus is applied only to such cases of itching of the skin as are unattended with alterations in the skin and are

independent of other diseases of the skin. The itching is generally aggravated by heat, and is therefore especially marked at night, preventing sleep, and consequently inducing serious debility. Generally the skin is covered with scratch-marks and cicatrices, and if the disease has existed for a considerable length of time the skin acquires a brownish color and infiltrated character, in consequence of transformation of the hemoglobin of extravasated red blood-corpuscles and inflammatory irritation of the skin. The duration of pruritus depends upon the removability of the causative factors. The prognosis, likewise, is governed accordingly, for although itching of the skin is of itself an annoying rather than a dangerous disorder, it is, however, not rarely dependent upon the presence of incurable diseases. Exasperating pruritus has occasionally led to suicide.

Etiology.-Cutaneous pruritus occurs not rarely in advanced life-senile pruritus-and is then probably dependent upon involutional processes in the cutaneous nerves. Frequently it is the result of auto-intoxication. It occurs, therefore, in association with jaundice, diabetes, nephritis, carcinoma, gastric, hepatic, and uterine disease, and during pregnancy. Some patients are attacked by pruritus on the approach of winter-hiemal prurituswith regard to whose mode of origin nothing is known. Occasionally pruritus occurs as an hallucination, as, for instance, in individuals that believe themselves the victims of cutaneous parasites.

Treatment. For the relief of cutaneous pruritus inunctions of carbolated ointment particularly may be recommended :

R Carbolic acid,
Wool-fat,

Lard,

For inunction twice daily.

5.0 (75 grains);

each, 25 (6 drams).—M.

Friction with lemon-juice or ablutions with dilute vinegar occasionally afford great relief.

administered:

R Potassium bromid,

Extract of belladonna,

Internally potassium bromid may be

Carbolic acid,

Extract of licorice, sufficient to make fifty pills.-M.

Dose: One pill four times daily.

Sodium salicylate and salophen (each 1.0-15 grains-every two hours) also have been recommended. In addition, the primary disorder should be treated.

VI. PARASITES OF THE SKIN (PARASITIC DER

MATOSES).

ANIMAL PARASITES OF THE SKIN (DERMATOZOÖNOSES).

ITCH (SCABIES).

Etiology and Anatomic Alterations. -The symptoms of scabies are due to the itch-mite, Acarus scabiei, or Sarcoptes hominis. Healthy individuals acquire the parasite either through

FIG. 36.-Female, sexually mature itch-mite, viewed from the dorsal aspect; magnified 300 times (after Kaposi).

intimate association with a patient suffering from scabies, or through the use of articles of linen or clothing that had been previously worn by such a patient and had become thereby infected with the itch-mite, or, finally, through infection from animals, for