pharynx, there is commonly a sudden eructation of air from the oesophagus, proving that with the apnoea there was closure of the pharynx at its lower extremity, as above described. Hence, there is reason to believe that the pharynx is the essential seat of cough.

DRAWING OF THE PHARYNX IN ITS CONTRACTED STATE, AS DURING THE FIRST PART OF THE ACT OF COUGHING.

1. Uvula contracted, and drawn upwards. 2. Tonsils drawn forwards and inwards.

3. Pharynx drawn forwards and inwards, and corrugated into folds. 4. Upper edge of epiglottis rendered convex, and applied to the posterior wall of the pharynx.

But it is believed that irritation set up in other and distant parts produces cough also, as, for example in the bronchi, the pulmonary structure, or even in the stomach. It is, however, to be borne in mind that the degree of irritation as a cause of cough which is observed when foreign bodies have passed through the larynx into the bronchi is by no means so great as is observed when irritants are directly applied to the pharynx; also,

that the amount of cough bears no relation to the amount of irritation existing below the larynx, and that stomach affections usually exist without producing any cough. When cough is owing to these causes it occurs through reflex action upon the pharynx, and hence in all cases it is proper to regard the pharynx as the true seat of this expiratory act. The importance of this question is evident, both with regard to the causes and the treatment of cough, and to these we shall have further occasion to refer.

As we have already shown that there is hyperæsthesia of the pharynx in a large number of cases of early phthisis, it follows that there will be a tendency to the occurrence of cough, and the amount of cough will (within certain limits), be in proportion to the amount of the hyperesthesia. As a general observation it may, however, be stated, that at the period in question the amount of cough is not usually a distressing feature in the case.

The nature of the cough is commonly short, and repeated a few times at each attack. It is not usually violent or causing much succussion, but sometimes it is spasmodic. It more frequently occurs on moving into a cooler atmosphere, as on going into the hall from the warm sitting room, or out of doors, or into the bedroom at night, and is consequently more frequent on taking out of door exercise, and at night. It is also immediately excited when, with a hot and perspiring skin, the clothes are suddenly removed, or cold air gains access by any means. It is not infrequently irritable in the early morning, and especially soon after rising,

and doubtless from a similar cause, for at that period of the day the temperature is commonly low. It is also worse in the colder seasons of the year, as the end of autumn, the winter, and the early spring, and is then more frequent throughout the day. A dry frost, however, although it causes cough, is not so constant a cause as a cold and raw atmosphere, and particularly one in which there is fog and smoke, and the latter condition is perhaps the most injurious of any in which such a patient could be placed. All these influences seem to have one common mode of attack, namely, the inhalation of air which irritates by the temperature or other qualities, and the effect is always greater in proportion to the volume of air inspired, the intensity of those qualities, and the sensibility of the mucous surface over which the air passes.

There are also numerous cases in which the cough is increased after meals. Such are commonly instances in which there is much general sensibility of the nervous system, and of the pharynx in particular, and in which the vital capacity of the lungs is much diminished; but in many instances it is due to food which produces irritation as it passes over the pharynx, or remains in small particles attached to it, or excites the reflex action from the stomach to which we have referred. The cause of this cough is not at all times easy of detection, but we have been accustomed to seek it in two directions :1st. It will manifestly arise if the food mechanically irritate the sensitive mucous membrane of the pharynx, whether by being in large lumps from imperfect mastication, or containing condiments, as pepper, salt, or

mustard, or possessing inherent stimulating qualities, as spirits, or remain adherent to the membrane from an imperfect deglutition, or from the absence of fluid following the deglutition of solid food; and all these conditions are remediable. 2nd. It has appeared to us to have some connection with a diminution of the capacity of the thorax which follows a full meal, by the distended stomach pressing the diaphragm upwards, and impeding respiration; or it may be in part due to the fulness of the blood-vessels, and the increased innervation which follows a meal, in which the pharynx partakes in common with other parts of the internal organs. The point to which we desire especially to call attention is, that the cough is not usually or necessarily associated with the condition of the lungs, to which we shall have hereafter to particularly refer; but whatever may be the immediate source of irritation, the seat of the cough is for the most part located within our reach.

CHAPTER XVII.

EXPECTORATION.

There is commonly a small amount of expectoration. In referring to the nature and quantity of the expectoration, it is necessary to premise that we discuss only those which commonly occur in the course of the disease, and not such temporary conditions as may be found in persons in health, or in every condition of disease.

The quantity of secretion expectorated is very small, and does not exceed from one-quarter to one-half ounce in the twenty-four hours. It usually occurs in the early morning and after meals, and follows a certain amount of cough which then prevails. During the other periods of the day its appearance is quite uncertain, and does not attract attention; but it is always associated with cough.

The nature of the expectoration is very uniform, except in the temporary condition of cold, &c., which we have excluded from consideration. It is semi-transparent, or only very slightly opaque, and not unfrequently shows lines or small masses of darker colour. It is never uniformly yellowish, greenish, or pinkish, and when these colours are found they are due to other