by columnar epithelium. Wherever this variety of epithelium is present, the exudate from the blood does not become incorporated with the mucous membrane, but escapes to the surface and coagulates in a layer over it. It is therefore loosely adherent to the underlying tissues, being attached to it by fibrinous threads, and, when it is peeled off, the hyperemic and swollen mucous membrane is seen beneath in its entirety, unless, as is commonly the case, a considerable part of its epithelium has been shed and been expectorated. The loose attachment of the pseudo-membrane in the trachea and bronchial tubes is of the greatest significance in its relation to tracheotomy.

I wish, in this connection, to call attention to the confusion which may occur in the use of the terms diphtheritic and croupous, as employed by pathologists, on the one hand, and clinical observers or practitioners, on the other. Pathologists, following Virchow, designate the inflammation as diphtheritic, when the epithelium and the underlying tissues remaining in situ are blended with the exudate and become a part of the pseudomembrane, whatever may be the cause of the inflammation; and they call the inflammation croupous, whatever be its cause, when the exudate escapes to the surface of the mucous membrane, as in the trachea and bronchial tubes, and coagulates upon it. Therefore, in all cases of pseudo-membranous inflammation of the airpassages, even that due to "taking cold," or to inhalation of an irritating vapor, they term the laryngitis diphtheritic, because, in the larynx, the exudate is incorporated with the mucous membrane; while the pseudo-membranous tracheitis or bronchitis in the same patient is termed croupous, because the exudate lies on the surface. Practitioners, on the other hand, apply the term diphtheritic to all inflammations which occur as local manifestations of the specific disease known as diphtheria, and to such inflammations only, whatever may be their form, whether pseudomembranous or catarrhal.

The epithelial cells embraced in the pseudo-membrane undergo a histological change. I have already referred to Ziegler's remark, that they are permeated by the exudate of the blood. Cornil and Ranvier say: "Wagner admits the fibrinous de

generation of the cells. . . . We have verified the description given by Wagner, but we would conclude that the cells are filled with a material which approaches mucin rather than fibrin."

In the first week, the pseudo-membrane forms more rapidly, is usually thicker and more extended, and produces dyspnoea more quickly, than when it forms in the declining stage of the disease. If the membrane be detached by the forcible coughing of the patient, it is usually reproduced promptly, unless the diphtheria be in its advanced stage and abating. If the croup continue from four to six days, the pseudo-membrane begins to soften and disintegrate from decomposition. The minute fibers which attach it to the membrane give way, and, in favorable cases, it is thrown off by the effort of coughing or vomiting. Separation is aided by the presence of muco-pus which collects beneath.

Symptoms. Whenever croup is one of the local manifestations of diphtheria, such general or constitutional symptoms are present as pertain to this blood-disease; such as febrile movement, anorexia, thirst, and progressive loss of flesh and strength. The temperature in the beginning in croup from this cause is usually higher than at an advanced period, unless some complication occur, such as pneumonia, which increases the heat of the system. The temperature is not, however, in the beginning, ordinarily above 103° or 104°; and, as the croup continues and the systemic blood-poisoning becomes more marked, the temperature usually falls, so that, even in the gravest cases, it is often at or below 100°. Most patients also have certain inflammations which commonly attend diphtheria, such as pharyngitis and coryza, but they are relatively unimportant in comparison with the croup, for, unlike the croup, they do not in themselves involve immediate danger to life.

Croup commonly begins gradually and insidiously, and is first revealed to the physician by hoarseness or huskiness of the voice and a hoarse or harsh cough. Both voice and cough are feeble, lacking the fullness and sonorousness present in spasmodic laryngitis. In grave cases approaching a fatal termina

tion, the voice becomes more and more indistinct, and finally is suppressed. The cough also, which, in the beginning of the croup, was strong and expulsive, becomes feeble and ineffectual, and is less frequent as the fatal result draws near.

The quantity of sputum varies considerably in different cases. If the inflammation extend no farther downward than the trachea, it is scanty; but if there be co-existing bronchitis, it is more abundant, consisting of muco-pus with occasional flakes of pseudo-membrane. By vomiting, a larger quantity is expelled than by the cough. Occasionally, masses of pseudo-membrane of considerable size are expectorated, or even molds of some part of the respiratory passage, always with great temporary relief to the patient. A pseudo-membrane of considerable thickness and extent obstructs the expectoration of muco-pus, which, collecting in the lower part of the trachea and in the bronchial tubes, greatly increases the dyspnoea. The respiration is somewhat more frequent than in health, but it is not notably increased except when bronchitis or broncho-pneumonia is present. At an advanced stage, when stupor supervenes from non-oxygenation of the blood, the respirations may be slower than in health.

Croup, in its first stages and in the active period of diphtheria, seldom abates or remains stationary, without treatment. Little by little, or often quite rapidly, the laryngeal stenosis increases, and soon the patient begins to experience the want of air. He becomes restless, has an anxious expression of countenance, seeks change of position, and reaches out his arms to the mother or nurse to obtain relief. In some patients only a few hours elapse, and in others a day or more of gradual increase in the obstruction, when it becomes evident that death must soon occur unless relief be afforded. In this stage, the postclavicular, infra-clavicular, supra-sternal, and infra-mammary regions are depressed during inspiration, and the larynx is drawn toward the sternum with each inspiratory act. While there is constant suffering, there are also most distressing occasional attacks of dyspnoea, attended with an increase in the lividity of the features and extremities, which now have a persistent

dusky pallor. Sometimes these attacks are perhaps due to the doubling of a detached end of the pseudo-membrane on itself, or perhaps to a movement of the muco-pus, by which bronchial tubes are occluded. With the ear applied over the larynx or the upper part of the sternum, a loud rhonchus is heard, both on inspiration and expiration, produced by the passage of air over the obstruction, and obscuring to a great extent the other sounds. Moist bronchial râles are also common.

Those who recover from membranous croup by the use of inhalations and without tracheotomy (and thus far they constitute only a small minority of cases), usually improve gradually, the obstruction diminishing as portions of the pseudo-membrane soften and become detached, the cough becoming looser, and the voice less hoarse. After the detachment of the pseudomembrane, several days elapse before the thickening and infiltration of the mucous membrane disappear and the epithelial cells are restored.

Diagnosis. Catarrhal laryngitis, with an unusual degree of thickening and infiltration of the mucous membrane and the underlying connective tissue, so as to produce stenosis and obstruct respiration, may be mistaken for pseudo-membranous inflammation. In the New York Foundling Asylum, two children have at different times died with the symptoms of membranous laryngitis, and the obstruction was found to be due entirely to thickening and to infiltration of the mucous and submucous tissues of the larynx and trachea with newly-formed corpuscular elements. Of course, death from catarrhal laryngitis is rare; but that this disease may produce such a degree of laryngeal stenosis as to cause even fatal dyspnoea, like that from the presence of pseudo-membrane, these two cases show. In most instances, the differential diagnosis between membranous and catarrhal laryngitis is rendered easy by the presence of patches of pseudo-membrane on the fauces, or by the history of the case, which may evidently point to diphtheria as the cause. I have elsewhere alluded to a child in my practice, who died with the symptoms of acute laryngeal stenosis, without any pseudo-membrane upon visible parts and with only a moderate.

pharyngitis. This case, which might have passed as one of catarrhal laryngitis accompanied by an unusual amount of cellular and serous infiltration, as there was no known diphtheria in the vicinity, was really due to diphtheria, and was a local manifestation of that disease; for, immediately after the death of the patient, the two nurses had unequivocal symptoms of diphtheria. The difficulty in using the laryngoscope in young children is such, when their fauces are swollen, that it has not heretofore aided much in the differential diagnosis of the various forms of acute laryngeal stenosis in young children, at least 'when employed by the general practitioner.

Prognosis.-The mortality from croup obviously depends to a great extent on the prevalence and the type of diphtheria. From what has been stated above, it follows that croup is more frequent and more fatal in a grave form of diphtheria than in mild epidemics. In New York city, during the fifteen years ending with 1878, the percentage of recoveries was very small, both under medicinal treatment and tracheotomy. During this long period, surgeons, not saving more than from three to five per cent of their cases by tracheotomy, performed this operation reluctantly; but since 1878, the percentage of recoveries after tracheotomy has been much greater. The mortality from croup is greater, the younger the child; for the younger the age, the less the diameter of the air-passages, and the more quickly laryngeal stenosis results. The younger the child, also, the more difficult is the use of the proper remedies, and the less time is there for their use, before fatal dyspnoea

occurs.

I have already said that croup appearing in the declining stage of diphtheria is less severe and more easily controlled or cured than when it occurs during the first stages. Much depends, also, upon whether the physician is summoned at the very beginning of the croup, and appropriate remedies are early and persistently employed. In many instances the friends do not take alarm, and the physician is not summoned until the disease is well under headway and there is not the requisite time for the action of inhalations. Obviously, also, croup, beyond all other