circumstances, change of air will often remove the cough as if by magic; and the shower-bath, and iron in some shape, will sometimes succeed if change of air be not practicable."

But, at what point in the course of the malady does habit assume the reins? I venture to say that the whole of the whooping or paroxysmal cough is an affair of memory in the reflex nervous mechanisms, like the post-catarrhal habit-cough of adults. Whooping-cough, as we all know, is often highly catching; but even when it is caught from others, it is caught as a catarrh—a catarrh which is followed after a fortnight, more or less, by paroxysms of coughing.

There are, indeed, those who ascribe infectiveness (where it exists) to the convulsive cough in and by itself, regardless of any antecedent catarrhal stage. Thus, Cohnheim says (1. c., ii, 206): “I think that we must consider tussis convulsiva to be an infective cough. For, not only is it an old experience that in whoopingcough only a small quantity of secretion is produced from the mucous membrane of the air-passages; but all impartial observers are agreed that the inflammation in the larynx as well as in the bronchi is in no sort of proportion to the intensity of the paroxysms of coughing. Such being the case, is it too much to assume that the virus of whooping-cough gives rise to the seizures of coughing by direct and immediate excitation of the laryngeal or bronchial mucous membrane, and without the intervention of a laryngobronchitis ?"

There may be cases of whooping-cough where the usual catarrh at the outset is too slight to attract attention; but it is not from these that we get the true sequence of events. In a typical case, the paroxysms of coughing are "in no sort of proportion to" the catarrh, for the excellent reason that the catarrh does not coexist with them but precedes them. The paroxysms of cough ending with a peculiar indraught of the breath are the after-effects of catarrh in infancy and childhood, whether the catarrh had arisen in an ordinary way, as in the course of measles, or in those epidemic visitations when pretty well everyone is coughing and sneezing, or whether it had been caught from someone suffering with a cold or suffering with whooping-cough itself.

The true sequence of events is well enough understood in the nursery, where the mother expresses fear lest the child's cold should "turn to whooping-cough." Catarrh in a child may be followed for days or weeks by paroxysms of dry coughing, with no whoop; or, again, there may be only an occasional whoop at the end of the fit of coughing (usually in the night), with few or none of the choking symptoms. Even if the case does really "turn to whooping-cough," the practitioner will be apt to reckon it as a "spurious " instance of that malady, unless he is persuaded that the child had caught it from a previous case of the

same.

The distinction between "spurious whoopingcough and real is one of those refinements that our

.

patients cannot understand; the symptoms are the same, the treatment is the same, and the issue is not by any means safer in the one than in the other. For my own part, if there is to be any distinction between spurious cases and real, I think the real cases of whooping-cough are those which arise out of epidemic coryza, or out of the catarrh of measles, or as the sequel of bronchitis in a rickety child or during the irritation of teething or under other predisposing circumstances; and that the spurious cases are those which are arbitrarily induced in the healthy by contagious particles from cases of the former class or from other cases of their own class; and I should maintain the reality of the former even if they could be shown, as they probably can be shown, to be very much fewer than the latter. Without entering upon the controversy,* I pass to my more immediate object of analysing the paroxysms of whooping-cough as the aftereffects of catarrh in susceptible children, or as the memories of bronchial irritation remaining on the reflex mechanisms of the breathing for some time after the catarrh had subsided.

If whooping-cough is in some striking particulars different from the dry cough that occasionally follows the catarrh of grown persons, it resembles the postcatarrhal cough of adults in being paroxysmal. In both cases the cough assumes the character of violent

* I had written at some length on the question of whooping-cough being always the result of a specific virus; but I find the subject so well treated by Dr. Sturges in the Med. Times,' 4th July, 1885, that I will refer the reader to him.

fits after the acute or febrile catarrh has practically ceased, and when there is nothing in the state of the air-passages to account for it. If these paroxysms are due to lingering memories of reflex excitation, it must be admitted that the memory is much worse than the reality. This point will come up again.

The special characters of the post-catarrhal stage of whooping-cough are only such as are proper to paroxysmal coughing in infancy and childhood. They are the familiar characters of a fit of whooping-coughseveral quick and shallow expirations, the violent distress of dyspnoea (from a stock of air soon exhausted), a long crowing breath of relief, and that cycle repeated twice or thrice, just as the paroxysm in the adult is made up of one series of coughs after another. The peculiarities of the paroxysm in a child, which make whooping-cough so remarkable a disease, will be best understood by taking into account the peculiar characters of a child's breathing. I take them as follows from Vierordt's 'Physiology of Childhood :'*

Respirations shallow and frequent, two or three times as rapid as in the adult; abdominal or diaphragmatic in both sexes alike until the tenth year; apt to be more irregular in rhythm during the first year than afterwards; and in particular apt to be interrupted by long involuntary pauses in the breathing, leaving no ill-effects and due to no diseased action. Furthermore, the breathing of the first few months is distin* Physiologie des Kindesalters,' Tübingen, 1877, p. 82.

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guished not only by the irregularity of the respirations in following one another, but also by the fact that their depth and rhythm change under very slight influences, as when one of those breath-holding pauses is followed by a number of short and shallow breaths and these again by one or two deeper and slower.

As regards the larynx, the posterior space of the glottis, or so-called cartilaginous glottis, is but little developed before puberty, "so that a paralysing effect on the muscles that widen the glottis has a much greater influence on the breathing in the young than in the full grown" (1. c., 84). Male children begin to be distinguished from female in their respiratory apparatus and mechanisms long before puberty. Crowing inspiration may occur in infants when there is nothing amiss.

In these various peculiarities of the breathing in childhood there is a sufficient basis for the peculiar characters of the paroxysmal cough of that time of life. Where the breathing is naturally rapid and proportionately shallow, a paroxysm of coughing is bound to bring on the struggle of impending suffocation, the struggle, namely, to fetch a deep breath. It is this prolonged indraught of air at the end of the three or four expirations that essentially distinguishes the paroxysmal or convulsive cough of infancy and childhood. The whooping or whistling sound that accompanies it is due to the spasmodic state of the glottis, a state of spasm that is itself caused by the exhaustion of repeated expirations. Expiration repeated several