3rd. Where the cerebro-spinal system is the recipient of the irritation which is the provocative of the attack-for example, that remarkable case related to me by Dr. Chowne, in which the application of cold to the instep immediately produced the asthmatic condition.

Of these two last groups of cases, I know of very few examples, and I may dismiss them with a few words. A case came under my observation some years ago in which a patient could regulate his asthma entirely by the condition of his bowels. They were, as a rule, relieved every evening; if the customary relief took place, and he retired to bed with an empty rectum, he awoke the next morning well; but if he neglected to relieve his bowels, or his efforts to do so were abortive, he was quite sure to be awoke towards morning by his asthma. Strange as this may appear, it is strictly true. Dr. Copeland remarks that the attack is often preceded by costiveness and inefficient calls to stool-an observation quite in accordance with the case I have just related. I should be disposed to think my self that these were not only precursory and premonitory symptoms, but that they had something to do with the causation of the asthma that followed them--that the attack had a propter as well as a post relation to them. Of a strictly analogous nature are those cases of hysterical asthma in which the attacks are preceded by recognised symptoms of uterine irritation. The remarkable case communicated to me by Dr. Chowne, to which I have already referred, was as follows: -J. G., a man of about fifty years of age, made application to an insurance office for the assurance of his life. In reply to the questions of the physician of the office, he stated that he was liable to spasmodic asthma. He stated that he was subject to these attacks if by any accident cold water fell upon his instep, or his instep became cold. The impression on the mind of my informant, who was the medical man who examined him, was that this was the commonest, but he is not sure it is the only, cause of the attacks. The asthma came on suddenly and immediately, and the attacks were very severe. The circumstances were considered so curious, that great pains were taken thoroughly to sift the case, and the result was that the facts were clearly established, and the man's life refused in consequence.

But while cases illustrating in this remarkable way the excito-motory nature of asthma, and the distance from which stimuli may reach and influence the innervation of the lungs, are rare, cases of peptic asthma, in which the attacks are caused by pneumogastric irritation, are so common, that I think few cases could be found of true spasmodic asthma in which the disease is uninfluenced by the state of the digestive organs, while in a very large number it is under their control. This fact is so patent and so generally recognised that it has by many writers been made the basis of their classification of asthma; thus Dr. Bree and Dr. Young erect into a distinct species those cases that are dependent on gastric irritation. Therapeutically, the full appreciation of this fact is most important; more is to be done for our patients on the side of the stomach than in any other direction. An observant and thoughtful physician once said to me that he considered dietetic treatment the only treatment of asthma.

But there is yet again another class of cases that have suggested to my mind the belief that asthma is sometimes central, not reflex, in its origin; that it may originate in irritation of the brain itself, or the spinal cord. The two following cases appear to me to be examples of this kind of "central" asthma. The first was communicated to me by my brother, Mr. James Salter, and occurred under his own observation. The patient was a boy of about ten years old, and the disease acute hydrocephalus, which ran a fatal course in about a fortnight. Five days before his death he was suddenly seized with an attack of dyspnoea of the asthmate kind; it was very severe, lasted about half an hour, and then entirely vanished. The following day he was seized with a precisely similar attack; but this was the last; the symptoms never reappeared, and the patient sank in the ordinary way, from the brain disease, about four days afterwards. He had never before suffered from asthma; there were no chest symptoms either before or after the attacks—

no cough, no expectoration. My brother is very precise as to the nature of the dyspnea; he says there was nothing cardiac about it-no panting, no orthopnoea -but that it had the labouring "difficult" character of asthma. I conceive that in this case the bronchial spasm was a phenomenon of deranged innervation from central irritation analogous to the jactitations, rigidity, and convulsive characteristic of hydrocephalus.

The other case was that of a man of about fifty years of age, subject to epilepsy. His fits had certain well-known premonitory symptoms, and occurred with tolerable regularity, I think about once a fortnight. On one occasion his medical attendant was sent for in haste, and found him suffering from violent asthma; the account given by his friends was, that at the usual time at which he had expected the fit, he had experienced the accustomed premonitory symptoms, but instead of their being followed, as usual, by the convulsions, this violent dyspnoea had come on. Within a few hours the dyspnoea went off and left him as well as usual. At the expiration of the accustomed interval after this attack, the usual premonitory symptoms and the usual epileptic fit occurred. On several occasions (I do not know how many) this was repeated, the epileptic seizure being, as it were, supplanted by the asthmatic. Of these four points my informant, who was the medical attendant, seemed certain; that there was nothing amiss with the lungs either before or after the attacks, that the character of the dyspnoea was asthmatic, that each attack of asthma occurred at the usual epileptic period, and that they were preceded by the premonitory symptoms that ordinarily ushered in the epilepsy. I think such a case admits of only one interpretation-that the particular state of the nervous centres, that ordinarily threw the patient at certain periods into the epileptic condition, on certain other occasions, from some unknown cause, gave rise to bronchial spasm; that the essential diseased condition was one and the same, but that its manifestations were altered, temporary exaltation and perversion of the innervation of the lungs supplanting unconsciousness and clonic convulsion. Bearing in mind the many points in their clinical history that asthma and epilepsy have in common, this case is one of peculiar interest.

To this same category of central asthma we must, in strictness, assign those cases in which the paroxysm is brought on by violent emotion, as in that remarkable instance I have related of the gentleman who had, on two distinct occasions, violent spasmodic asthma suddenly induced by alarm, from the fear that he had poisoned his wife. In such a case, the seat to which the stimulus is primarily applied is the brain itself.

Lastly, there is a class of cases in which the exciting cause of the paroxysm appears to be essentially humoral. I have stated that the most frequent of the exciting causes of asthmatic attacks are alimentary, and that an error in diet, or the mere introduction of food into the stomach, produces bronchial spasm by reflex stimulation, through the intervention of the pneumogastric nerve. But is this the only way in which the lungs can be affected by what is put into the stomach? No. Although the pneumogastric nerve is the only single structure that has a distribution common to both organs, yet the venous system affords a very close and intimate bond of connexion between the stomach and the lungs; for, any rapidly absorbable material introduced into the stomach, is at once taken up by the venous radicles of the gastric mucous membrane, and within a few seconds, having passed through the liver and the right side of the heart, finds itself in the pulmonary circulation. In this way the blood in the lungs is liable to constant change in its composition, from admixture with it of the different materials thus taken up by the gastric veins; and, from the absence of secernent or elective power on the part of these veins, is ever at the mercy of the food. The chief parts of the normal results of healthy digestion, or the morbid results of depraved digestion, and that numerous class of bodies which are at once taken up without any change, are thus thrown directly upon the lungs. In the intestines we have an additional channel for the introduction of the contents of the alimentary canal into the pulmonary circulation; namely, the lacteal absorbents. It is, I believe,

in this way, by the actual presence in the vessels of the lungs of the materials taken up from the stomach and intestines, that the introduction of food into the alimentary canal frequently gives rise to bronchial spasm. A contaminate blood is the irritant, and excites the bronchial tubes to contract through the intervention of the pulmonary nervous system, just as the effluvium of hay or an irritating gas would. In one case the irritant affects the surface to which the nerves are distributed, in the other, the capillaries among which they lie. When I say a “contaminate” blood, I do not mean that the material present in it is necessarily peccant. I believe it may be perfectly normal, and yet produce asthma. I believe that digestion may be everything that it should be, and its results in no way different from that of a perfectly healthy person, and yet they shall, in an asthmatic, produce asthma the moment they arrive at the lungs. I believe this because some of the materials that give rise to asthma are such as undergo no change, but are at once absorbed, and must therefore necessarily be identical in the lungs of the sound man and in the lungs of the asthmatic, and also because many persons who are rendered asthmatic by taking food, exhibit no symptoms of deranged stomachaction whatever. One such case in particular, with which I am very familiar, is that of a lady who every day within a few minutes after commencing her dinner experiences that dry constricted straitness of breathing characteristic of asthma; even if she has her asthma at no other time, she will have it then; after lasting a quarter of an hour, or half an hour, it passes completely off. Now this lady's digestion is remarkably good, unusually powerful and rapid; she is free from the ordinary restrictions of diet that most people are obliged to acquiesce in--radishes, cucumbers, and other unwholesomes, agree with her perfectly well; and the production of the asthma does not depend upon the quality of the food, such things as I have mentioned do not seem to induce it, while she will often become asthmatic during the plainest meal. I believe in this, as in hay, ipecacuan, and other asthma, that the irritant differs not in the asthmatic and the healthy person, but that the essential difference is in the irritability of the pulmonary nervous system-that it resents that which it should not resent-that its morbid sensitiveness exalts that into a stimulant which should not be a stimulant, and that thus the pulmonary nervous system registers (as it were) on the bronchial tubes those changes in the constitution of the pulmonary blood of which it should be unconscious.

There are, however, certain articles of diet which, either from their being peculiarly offensive when materially present in the lungs, or apt to give rise to dyspepsia and its vitiated results, or specially irritating to the gastric portion of the vagus, are very apt to give rise to asthma. Such asthmatic articles of food are -cheese, nuts, almonds and raisins, and sweet things in general, salted meats, condiments, potted and preserved and highly-seasoned things, fermented drinks, especially malt liquors and sweet wines. I think malt liquor, especially the stronger sort, with a good deal of carbonic acid gas in it, is perhaps the most asthmatic thing of any; next to that I should place raisins and nuts. I know the case of an asthmatic gentleman who cannot eat a dozen raisins without feeling asthmatic. But there is great caprice about asthma in this respect, strongly marked idiosyncrasies in individual cases. Thus, in one case, a single glass of hock would invariably bring on an attack, though any other wine might be drunk with impunity; in another, Rhine and Bordeaux wines-hock and claret--were the only ones that could be drunk; a dinner at which they alone were partaken of was sure never to be followed by asthma, but if port or sherry were drunk, the asthma would infal libly come on within an hour or two. In another case the whole mischief of a dinner, its sting, lay in its tail, in the usual post-prandial coffee; if that vicious drink was declined, no harm came of the dinner, but if it was partken of, on came the asthma.

But why, it may be asked, do I choose to adopt the opinion that these different alimentary materials produce asthma by their material presence in the blood of the lungs, consequent on their gastric absorption? Why is not the supposition, that they act as irritants to the gastric portion of the vagus sufficient for the ex

planation of all cases? I do not say positively that it is not sufficient; I do not say it is not the sole way in which all these articles of diet excite asthma. But there is in particular one circumstance that makes me think that some of these materials at least, and in some cases, act by their presence in the lungs themselves, and it is this-that they induce the asthma in just such time as they would reach the lungs in subsequent to their absorption; the interval between the taking the material and the supervention of the asthma will be long or short, according as the absorption of that particular material is immediate or deferred. Thus, in a case which once came under my notice, in which the taking of wine or any alcoholic drink was always followed by asthma, the asthma was immediate, within a minute or two; while in another case, in which the food producing the asthma was such as would furnish material for lacteal absorption, the asthma did not come on till about two hours after taking the food, that is, when the chyle would be beginning to reach the blood being poured into the lungs.

But we must not forget that asthmatics are very commonly dyspeptics, and often exhibit symptoms of perverted and capricious stomach action, that suggest to one's mind the belief that the innervation of the whole of the vagus is vitiated, its gastric as well as pulmonary portion, and that the dyspeptic and asthmatic symptoms are but parts of a whole. I could mention some very interesting cases illustrative of this, if space permitted.

What I would wish, then, to express on this subject is-that I believe it possible that asthma is sometimes produced by particular materials admixed with the blood in the lungs, and that therefore it is so far humoral; but that these particular materials-whether absorbed unchanged, as alcohol, ethers, and saline solutions, or the results of heathy digestion, or of perverted digestion-have nothing particular in them, but are the same as they would be in any non-asthmatic person, and that the essence of the disease in these cases, as well as in all others, consists in a morbid sensitiveness and irritability of the pulmonary nervous system. Great and valuable light is often thrown on pathological questions by considering the laws of the physiology of the part concerned, for pathology is often but deranged physiology, and pathological aberrations in strict subservience to physiological laws. Let us, then, see if we can detect in the probable purpose of the muscular endowment of the air tubes, an explanation of any of the phenomena of asthma. What is the purpose of the muscular contractibility of the air passages? This is a question that has been variously answered, and whose certain solution is beset with considerable difficulties. In one light we may look upon the bronchial system as the ramifying efferent ducts of the great conglomerate gland the lungs, of whose excretion, carbonic acid, it affords the means of out-draught. Now the ducts of all large glands are furnished with organic muscle-liver, pancreas, salivary glands, kidneys, ovaries, so that the existence of muscular elements in the walls of the bronchial tubes is in strict conformity with anatomical analogy. But when we pass on from anatomy to function all analogy ceases. The purpose of the muscular endowment of the ducts of glands in general is the expulsion of the secretion; little waves of vermicular contraction pass along them, always in a direction from the gland, and thus their contents are driven along towards the orifice. Such cannot be the purpose of the muscularity of bronchial tubes, for they are permanently and necessarily patulous; indeed, throughout their greater length a special arrangement is adopted by which their closure shall be effectually prevented, by means of the little flakes of cartilage scattered throughout their walls. In the larger tubes these are such and so placed that only a slight amount of contraction is possible; they are continued down, in increasing tenuity and scantiness, to tubes of a smallness of half a line in diameter, and wherever they exist perfect closure is impossible; so that in none except tubes of extreme minuteness can perfect closure take place. But beyond the point of the cessation of cartilage flakes muscle still exists; it has been demonstrated in tubes th of an inch in diameter, and probably even in the ultimate lobular bronchiæ; here, of course, perfect closure can be effected.

What are the acts, then, of which the bronchial tubes, thus constituted, are the seat? Respiration and Cough. For we must consider cough a normal act. It is the constituted mechanism of expulsion of any particles of foreign matter which may at any time be introduced with the respired air, and against whose ingress the stricture function of the glottis so imperfectly provides. Indeed, the respiratory organs have no power of selection, no means of filtering the material on which they are every moment dependent for the exercise of their function; they are ever at the mercy of the air, and of any materials that may contaminate it. The power, therefore, of expelling any foreign or offending particle that may have found entrance, becomes a necessary appendage to respiration. Cough is, no doubt, often a phenomenon of disease, but it becomes pathological from the material on which it is exercised, and not from the essential nature of the act. If exercised on blood, pus, or excessive mucus, it is a symptom of disease; if on some foreign particle that has found accidental ingress, it is strictly normal. It is no more pathological than sneezing is pathological, which a particle of dust, or a sunbeam, may cause at any time. What purpose, then, if any, has the muscular endowment of the air passages in relation to these two acts-respiration and cough?

It has been maintained by many that the bronchial tubes contract at each expiration, and so assist in the expulsion of the air. But the character of the fluid expelled-gaseous, and the method of its expulsion-quick, transient, and iterated, are neither such as the ordinary slow vermicular contraction of organic muscle would be appropriate for; it is impossible that the bronchial tubes can expel the expired air in the same way as the ducts of glands do their secretion, it is impossible that a wave of contraction can pass from extremities to trunk of the bronchial tree at each expiration; it would be a rapidity of transit entirely at variance with all that we know of the law of organic muscle contraction. Moreover, we know that uninterrupted patulence from glottis to air cell, both in inspiration and expiration, is an essential condition of normal breathing. If there is any bronchial contraction coincident with expiration, it must be a slight narrowing of all the tubes, which would act not as a special expiratory force, but would merely diminish the amount of residual air locked up in the air-passages at the end of expiration.

This slight contraction of the whole bronchial system at each expiration I am, for the following reasons, inclined to believe. I have long observed that rhonchus and sibilant râles are often only audible during expiration; that in inspiration they cease; that they are frequently confined to the end of an expiration, not becoming audible till the expiration is half performed; that the longer and deeper the expiration the louder they are; and that the inaudible respiration of persons in apparent good health, particularly the old, may be rendered wheezing by making them effect a prolonged expiration. I have remarked this, not only with the dry sounds of asthma, but the moist râles of bronchitis; the crepitons wheeze of senile bronchitis is often confined to the termination of the expirations. If you tell a person with unsound lungs to wheeze, he immediately effects a prolonged expira tion, as if he knew that that was the way to produce a wheeze. Now the source of sound-the plug of mucus, or the inflamed tumid membrane-exists as much during inspiration as expiration: why, then, should the sound be present in the one and absent in the other? On what does it depend? Manifestly on the alternate contraction and dilatation of the air passages. The plug of mucus, or the tumid membrane, which does not narrow the tube sufficiently to give rise to a musical sound in inspiration, in expiration does. I do not know how we can explain these phenomena except by supposing that all the bronchial tubes undergo contraction during expiration, and thus magnify the effects of any sources of inequality in their calibre; for a plug of mucus, for example, that would form hardly any impediment to the passage of air in a wide and patulous tube, would form a considerable barrier, and throw the air into strong vibrations, if that tube were in a state of contraction. Moreover, I have noticed (and this is a very curious fact)