of equal duration with it, so as to obscure it in some instances, and in others to mask it and render it inaudible; it may even be prolonged over the succeeding sound, and may obscure that also if it does not mask it altogether; but, on the other hand, it may be of short duration, and audible only at the commencement or at the close of the sound, which may be clearly distinguished in addition to the murmur. When once developed, these endocardial murmurs are usually persistent, except when the heart's action becomes very feeble, as at the approach of death, or during syncope or extreme exhaustion, in either of which cases they often become intermittent, or may even cease altogether, in consequence of the non-occurrence of the vibration necessary to their production. Cæteris paribus, they are more intense the greater the force of the current and the larger the volume of blood propelled past the obstruction; and if they disappear under any of the circumstances above referred to, they will usually be reproduced by anything which accelerates and increases the force of the heart's action, whether it be mental emotion or bodily exercise. For when a cause of murmur exists, the murmur may not only become soft or inaudible, when the heart's action becomes slow and feeble, but it may increase in intensity under the influence of an excited circulation and increased force in the action of the heart.

Endocardial murmurs are synchronous or nearly so with the ventricular systole, or the ventricular diastole, and hence are sometimes termed respectively systolic or diastolic murmurs, but inasmuch as in some instances they arise from the presence of disease which impedes the onward flow of blood, and in others from disease of the valves which admits of the blood passing back through the auriculo-ventricular, or the arterial orifices, they are sometimes termed respectively obstructive and regurgitant murmurs.

But they may be not only systolic or diastolic and obstructive or regurgitant, they may be organic or else functional in their origin—in other words, they may be due to organic disease of the heart or great vessels, or to simple alteration in the quantity and quality of the blood, combined with functional derangement of the circulatory apparatus. In either case they are essentially connected with the production of an eddy in the current of the blood-a phenomenon which alone is capable of producing vibration such as that of which murmurs are the natural result.

Now, as eddies capable of producing sonorous vibrations do not exist

in a healthy state of the heart and great vessels, the presence of murmurs is a sure indication of some abnormal condition productive of eddies and vibrations. Practically, therefore, a murmur may be regarded as an audible announcement that something has occurred to roughen the surface of the endocardium or the internal coat of the great vessels, to constrict the great vessels or the orifices of the heart, to affect the elasticity of the great vessels, or to render the valves of the heart inefficient, so that they close imperfectly, or admit of regurgitation of the blood.

The mischief may be permanent or of temporary duration, of a structural or of a functional nature, and it may be either external to the organs of circulation or within the cavities of the heart or arteries. If the cause of endocardial murmur be external to the cavities of the heart and great vessels, it must be of an organic nature, and must produce its effect by exerting pressure upon them.

Thus, inflammation of the pericardium, when very acute and of long duration, is apt to impair the elasticity of the coats of the arteries, and, by the exudation which attends it, may lead to constriction of the great vessels at their origin. So, again, malformation of the chest walls and tumours in the thoracic cavity, by compressing the heart or the great vessels, may alter their shape, and excite undue vibrations and murmurs; and so also may the pressure of consolidated lung on the pulmonary artery or some of its branches, and of enlarged bronchial glands or any other intrathoracic tumour.

Endocardial murmurs, due to organic or structural mischief within the organs of circulation, are very numerous. They may be attributable to malformation of the heart, and to the consequent meeting of conflicting currents of blood, to disease in the valves, the chorda tendineæ, or the papillary muscles, or in the orifice of one of the great vessels, or in the great vessels themselves. The mischief in each case may be of a different nature. The more common causes of endocardial mischief, are, 1st, inflammation, which produces vascular injection of the valves and other parts of the endocardial membrane, followed by infiltration of their texture, and by the deposition of fibrinous granulations on their surface-changes which usually lead to permanent thickening, rigidity, and contraction of the valves, and of the tendinous cords, or to roughening of their surface, but which may result in the cohesion of two or more adjacent tendinous cords, or of two valves, or of two parts of the same valve, by means of coagulable lymph, or even in the softening and

ulceration of the parts, and so to the rupture of a valve or a tendinous cord. The most frequent results, therefore, of this form of disease, are insufficiency of the valves, or roughening of their surface, with constriction of the orifices of the heart, and consequent obstruction to the circulation. No diseases are more provocative of this form of mischief than acute rheumatism and Bright's disease of the kidneys. 2ndly. Chronic degeneration of structure, whereby atheromatous or calcareous matter is deposited in the valves, or in the coats of the artery, leading to impaired contractility of the artery, and to thickening and roughening of the surface of both valves and vessels. 3rdly. Enlargement and dilatation, whether aueurismal, or otherwise, of the walls of the heart, whereby the orifices of the great vessels often become enlarged to such a degree that the valves prove inefficient to close them, or the papillary muscles so much affected as to lose their regulating power over the auriculoventricular valves. 4thly. The presence of coagula in the cavities of the heart-a cause, which, presumably, never comes into operation except towards the close of life, when the circulation is slow and languid. 5thly. The sudden rupture of a valve, in consequence of a blow or some violent straining effort.

Drs. Blakeston, Walshe, and others, maintain that dilatation of the ventricle, by rendering it "more spherical and less convergent to its arterial outlet," may cause misdirection of the blood-current, and thus excite murmur. But the idea is founded entirely on misapprehension. If the ventricle at the moment of contraction were partly empty, then might conflicting or eddying currents occur, and the theory would be entitled to some consideration. But, inasmuch as the idea of a vacuum in the heart during life is a simple absurdity, the cavities of the heart being necessarily at all times filled with blood to the full extent of their dilatation, it follows that contraction of their walls can have no other effect than to act upon the mass of blood within, and force it through any outlet which offers; and, inasmuch as the contracting or propelling force is exerted on all sides, and the current, if the auriculo-ventricular valves are sound, can only be in one direction, the shape of the ventricle cannot possibly exercise the slightest influence in the production of murmur. The murmur in the cases referred to is more probably referable to impaired elasticity and contractility of the artery, and to the eddying of blood consequent thereupon.

Endocardial murmurs, due to functional or inorganic causes, do not so readily admit of explanation. It seems impossible to doubt that

murmurs do sometimes arise in cases in which no structural mischief exists; for not only are they met with during the progress of rheumatism, typhus fever, and other disorders unattended by any general symptoms of cardiac disease, but they are often excited by hæmorrhage and other causes productive of anæmia and spanæmia. Further, they are known to disappear completely under circumstances which improve the general health and yet do not exercise any specific influence on the heart. A question, however, arises respecting their causation. It is commonly asserted that these functional murmurs are directly referable, in most cases, to an impoverished and spanæmic condition of the blood; and, in proof of this position, the facts are cited, that these murmurs often follow venesection or hæmorrhage, and are usually met with in pale, anæmic persons. There cannot be a doubt as to the facts themselves; but I am inclined to question the inference drawn from them. True that murmurs often arise under circumstances productive of anæmia and spanæmia, and that these murmurs are usually of functional origin, or, in other words, unconnected with structural disease. But it is equally true that functional murmurs are not unfrequently met with in florid persons, who present no appearance either of spanæmia or anæmia, and it is also true that they are often absent in anæmic persons, and even in persons blanched by hæmorrhage. Further, it is certain that nervous excitement, which produces palpitation, will often given rise temporarily to a murmur in persons who are not spanæmic,† and that

* A case of this kind is at present, (January 7, 1862) under my care, in the person of Catherine Ward, aged fifty, who is in the Pepys Ward of St. George's Hospital. Although thoroughly blanched, as the result of profuse hæmatemesis, no murmurs of any kind accompany the sounds of the heart.

†This has been often forced on my attention during the examination of persons about to assure their lives. Only last month I met with a remarkable case in point. A gentleman, aged thirty-nine, presented himself for examination. His life had been refused at one office in consequence of his having a cardiac murmur, and he was extremely nervous. A systolic murmur intensely loud at the left apex, and also at the right and left base of the heart, led me in the first instance to consider that his heart was seriously diseased, and that his life was uninsurable. He declared however that he had not had a day's illness for above twenty years, and that he was not short-breathed, and never suffered from palpitation except when he was nervous; and as the area of præcordial dulness was not increased and the impulse of the heart was not of a heaving character, as it ought to have been had he suffered long from regurgitant mitral and obstructive aortic disease, but was rather of a knocking, nervous character, I thought it possible that the murmurs might be functional. He was therefore requested to come to me another day, and after a few interviews, when his nervousness had subsided, the murmurs entirely disappeared.

*

even in the individuals in whom this is observed, bodily exercise, though it produces increased action of the heart, and forcible impulse, may fail to excite a murmur. Again, it is true that in many cases of chorea, in which there is neither anæmia nor spanæmia, a functional systolic murmur may occur both at the base and apex of the heart-a murmur, which, at the apex at least, cannot be referred to the condition of the blood, but must be attributable to regurgitation of blood through the auriculo-ventricular opening, and therefore must be connected with a disordered action of the apparatus which regulates the valve. If then, neither anæmia nor spanæmia, nor both combined, will necessarily produce a functional murmur; if functional murmurs may arise in cases in which neither anæmia nor spanæmia exists; and, further, if functional murmurs are met with which are obviously connected with irregular action of the valves, may not all functional murmurs be referable to irregularity in the action of the valvular apparatus, consequent on perverted innervation and disordered action of the elastic tissue of the valves? Any excess or deficiency in the elasticity of the tissue on which the action of the valves and the large vessels depends, would necessarily lead to an eddying of the blood, and so to the production of murmurs. It is certain that, even when spanæmia and anæmia exist, functional murmur is commonly confined to cases characterised by palpitation—a result of nervous irritability—and that profuse venesection, hæmorrhage, and other causes of spanæmia, are also productive of palpitation, and of exalted nervous excitability. Therefore, without denying that an anæmic and spanæmic condition of the blood must necessarily facilitate the production of vibration and murmur, it seems to me probable that these functional murmurs are more closely connected with perverted innervation and disordered contractility of the valves and large vessels than with a mere alteration in the condition of the blood.t

* The forcible propulsion of healthy blood by an hypertrophied heart has been stated by Dr. Walshe (loc. cit., sec. 1303) to be capable of generating direct murmur. The frequent, nay, the usual absence of direct murmur in cases of simple hypertrophy, however fully developed, is sufficient to negative the theory alluded to, and it is probable that the murmur which arises in some of the cases alluded to is connected with some irregularity in the action of the valvular apparatus, or with some deficiency in the elasticity or contractility of the aorta whereby an eddy is created in the current of the blood.

+ The mechanism of these functional murmurs is rendered intelligible by Dr. Broadbent's recent dissections of the valves, whereby it is shown that a layer of elastic tissue enters into their composition, the fibres of which run chiefly in a direc