not recognised in the others, the natural tendency of dilatation is to produce such a condition, it is not unfair to assume that it really did exist in some degree or other in every one of the series. When I add that the pathological records of the above cases were written by me at a time when I had no theory to maintain or to combat, and, in several instances, before any intimation of the cause of death had been conveyed to me, it will be seen that they do support in a very unmistakeable manner the theory which I have explained and am endeavouring to enforce. I may here adduce, in corroboration of my views, a case published by Dr. Hare in the Transactions of the Pathological Society' (vol. iii. p. 72), in which, with tricuspid murmur and regurgitation, there was no trace of valve disease, but great dilatation of the right ventricle and manifest atrophy of the musculi papillares. And I may state that in at least two or three other cases which have come under my notice, in which I have known that mitral regurgitation existed during life, but which, in consequence of no clinical notes having been preserved, have been rendered in great measure useless for my present purpose, the same remarkable smallness of the papillary muscles and their tendons was observed There is yet another condition, necessarily associated with dilatation of the ventricles and insufficient length of the chorda tendineæ and musculi papillares, which has not been adverted to, but which doubtless aids in some degree in the production and maintenance of valvular incompetence-I allude to the lateral displacement of the origins of the musculi papillares in consequence of the rounded form which dilatation imparts to the heart; and to the altered direction therefore in which the force of these bodies has to be exerted. Dr. Hare specially refers tricuspid incompetence to this cause in the case already quoted. In confirmation of the explanation which I have ventured to give, I may refer to Mr. Wilkinson King's well-known paper* "On the Safetyvalve Function in the Right Ventricle of the Heart." He there attributes the regurgitation which, as a normal process, takes place occasionally through the tricuspid aperture, to temporary over-distension of the thin and yielding ventricular walls, and consequent displacement and insufficient length of the musculi papillares and chorda tendineæ. He shows also how, from the close coaptation of the mitral valves, and from the comparatively unyielding state of the parietes, such regurgitation is impossible on the left side so long as the heart is in a healthy condition. But it is obvious that, as its cavity becomes enlarged and its walls comparatively thin, the left ventricle loses in some degree its own distinguishing features, and acquires in their place some of those peculiarities which naturally belong to its neighbour, and upon which its safety-valve function has been proved to depend. It must acquire with its peculiarities the liabilities which belong to them. And hence if we admit the truth of Mr. King's observations in reference to the healthy right ventricle, it is impossible not to admit their applicability to the dilated left; and it is equally impossible, I think, not to concede, in reference to both ventricles, that regurgitation, which may be Guy's Hospital Reports, No. 4. 1837. occasional only so long as the dilatation is confined within certain moderate limits, will probably become permanent so soon as these limits have been transgressed. 3. It follows from the previous observations that, in those cases in which incompetence of the mitral valve exists, without apparent disease of the valve itself (and the same holds good with respect to the tricuspid), the incompetence, important though it may be in its results, is not the primary malady; but must have been preceded for a longer or shorter period by an abnormal condition of the cardiac parietes. This' statement does not rest on theoretical grounds alone. Its truth is attested by such cases as that of J. Bunting, in which unmistakeable cardiac symptoms had existed long anterior to the specific signs of mitral regurgitation. But the best proof, perhaps, is furnished by the occurrence of cases resembling, in all essential respects, those which have been narrated, yet in which no cardiac murmur has at any time been recognised. Such cases are far from uncommon. I have met with many, but as they are foreign to my present purpose, refrain from introducing any of them here. The essential morbid condition preceding and causing incompetence of the apparently healthy auriculo-ventricular valves, I have shown to be dilatation of the ventricles of the heart; and since this forms the very foundation of the class of cases of which this paper treats, although I have nothing of novelty to impart in reference to it, I should almost feel myself guilty of disrespect were I to dismiss it without bestowing on it a few remarks. Dilatation of the heart is, as is universally allowed, a result and an indication of weakness of its muscular tissue. Weakness alone, however, can scarcely produce dilatation. Whence, then, does it arise? It is easy to give an answer to this question that shall receive general acquiescence, but far less easy, I suspect, to furnish specific proofs of the various propositions which that answer may comprise. Debility of the heart, however excessive it may be, provided the duties which the organ has to perform are adjusted to its capabilities, will not, as the records of phthisis and of cancer show, be followed by unnatural distension. A far lesser degree of feebleness, however, in a heart which is called on to act beyond its strength, will soon succeed in producing greater or less dilatation. Hence we may expect this condition to arise in chronic forms of non-fatal cachexia, where the heart's action is unduly affected by mental conditions, or where it is over-stimulated by too laborious occupation; anæmia, syphilitic dyscrasia, chronic malarious affections, debility from over-work, and insufficient food, may be cited as examples. Hence, too, it may not improbably be engrafted on attacks of acute disease, where the heart has been disproportionately affected, and where its progress towards recovery has lagged behind that of the rest of the organism. I allude to such affections as typhus, in which the heart is notoriously weakened to excess; small-pox, in which I have seen extreme fatty degeneration, and which, I think, probably initiated the cardiac disease in the case of J. Brownley; eruptive fevers generally; diphtheria and purpura, in both of which latter excessive fatty degeneration may occur; and other blood-diseases which need not be specified. And hence also we may, perhaps, occasionally meet with it in cases where the circulation becomes obstructed independently of heart disease, as in chronic bronchitis and in morbus Brightii. Age alone has evidently little influence, for the affection occurs with nearly equal frequency in the young, the old, and the middle-aged. It will, perhaps, be asked whether these dilated hearts are in a state of fatty degeneration. So far as the cases which have come under my notice are concerned, I may reply by an unqualified negative. In every instance the muscular tissue presented to the naked eye a perfectly healthy appearance, and in those cases in which it was subjected to microscopic examination the fibres exhibited slight, if any, deviation from the normal state. It should be borne in mind, however, that extreme feebleness and atrophy of voluntary muscular tissue may occur without any apparent structural change of the ultimate fibres, and there can be no doubt that the muscular tissue of the heart is also liable to be thus affected. It should also be borne in mind that unnatural thinning is virtual weakness; and that if dilatation and thinning have been produced by any temporary impairment of the ultimate tissue of the heart, these conditions are liable not only to continue, but even to progress, after the ultimate fibres themselves have resumed their healthy state. We must not, therefore, assume that the heart's tissues are really healthy because they look so; yet, neither must we take it for granted that they are really unsound because the presence of dilatation attests that unsoundness once existed. ART. V. Experiments on the Chromic-acid Test for Alcohol. THE following experiments were undertaken in Dr. Chambers' Laboratory at St. Mary's Hospital, with the view of testing the applicability of the process proposed by Messrs. Lallemand, Perrin, and Duroy, for the detection and comparative quantitative estimation of alcohol in organic tissues and excreta. An apparatus similar to that figured and described by the authors was fitted up, the principal differences being, that the aspirator was placed last instead of first in order, so that the air was drawn instead of forced through the apparatus. This form was adopted, as it was found that air passed through a caoutchouc tube turned the test-liquid first green and then brown, from the deposition of carbon. This arrangement also prevented the possibility of the escape of vapours through imperfections in the corks or joints, as, if such existed, a current inwards would be established. Another modification was, that the air was made to traverse a tube containing test-liquid before passing over the substance under examination. This arrangement served to show the action of air alone upon the test-liquid, and to prevent vapours capable of changing the test-liquid from entering the apparatus. The experiments of a negative character gave the following results: Air alone passed through the test-liquid, which has a bright orangered colour, causes it to assume a dark greenish-yellow colour. This effect is scarcely perceptible within one hour. Air carrying vapours from cerebral matter or from urine through caustic lime, does not affect the test-liquid more than air alone. Other experiments showed that after the ingestion of small quantities of alcohol, that body can be readily detected in the breath and in the urine. The experiments cited by the authors give no grounds for regarding the test as suitable for the comparative estimation of alcohol, and a few experiments made for the purpose of testing its applicability on this point, gave results by no means leading to such a conclusion. To ten c. c. of test-liquid in a tube upon which a stream of cold water was running to prevent rise in temperature, a very weak solution of alcohol was added from a burette. Fourteen measures of this solution were required to induce exactly the same green tint as was possessed by a portion of test-liquid to which an excess of alcohol had been added, but the tint produced by ten measures was only to be distinguished from it by careful comparison against a white ground. Another experiment gave the same result. Fifty burette measures of this weak solution of alcohol, when placed in the apparatus, served to give a green colour to three successive portions of test-liquid of two c. c. each. The shades of green were not the same in each case. One hundred burette measures of the alcoholic solution converted seven successive portions of two c. c. each of the test-liquid to a light green colour, the seventh only differing slightly in tint from the others. Of these, the last three portions were converted by the alcohol retained by the lime, the flask having become perfectly dry, and the lime requiring the application of considerable heat to drive off the vapours of alcohol. Twenty burette measures of the alcoholic solution served to turn five portions, equal to ten c. c. of test-solution, of a light green colour, though not the same tint as obtained by the direct addition of alcohol to the test-liquid. In this case also the greater portion of the alcohol had to be driven from the lime after the flask was dry. A number of other experiments point in the same direction. In order to drive the alcohol from the lime, it is necessary to apply such heat to it as drives off water, and sometimes organic matter, which, by giving a different colour to the test-liquid, renders it impossible to determine the end of the reaction. The time required when any great bulk of matter is to be operated upon, as in the case of urine, &c., is not the one hour and a half or two hours mentioned by the authors, but in some cases the process took as much as two days, and in consequence of the necessity for removing the lime, slaked from time to time, the results were useless, as perhaps as much alcohol was retained by the slaked lime as passed through it. [We regret that the correction of the proof of this article is rendered impossible by the death of the author.] PART FOURTH. Chronicle of Medical Science (CHIEFLY FOREIGN AND CONTEMPORARY). HALF-YEARLY REPORT ON PHYSIOLOGY. Fellow of the Royal College of Physicians, Physician to the German Hospital. I. GENERAL PHYSIOLOGY. 1. R. VON VIVENOT, Jun.: On the Influence of Change of Atmospheric Pressure on the Human Organism. (Virchow's Archiv, vol. xix., p. 492, 1860.) 2. W. W. GULL: An Oration delivered before the Hunterian Society, London, 1861. 1. VIVENOT has examined the phenomena observable in man when exposed to sudden alterations of atmospheric pressure. Rapid and considerable diminution of pressure, as experienced by the ascent in the air-balloon to the height of about 18,000 feet above the sea, or by the climbing of mountains of a similar elevation, connected with a reduction of pressure to one-half of what we are generally exposed to,-is found to cause: 1. Increased evaporation from the fungs and surface of the body; 2. Increased oxidation, in consequence of the loss of warmth occasioned by the augmented evaporation; 3. Increased frequency of respiration and pulsation, the former being induced as well by the smaller amount of oxygen contained in a certain volume of air, as also by the greater amount required in the formation of heat; 4. Congestion of blood towards the peripheric parts, and in consequence dilatation and even rupture of bloodvessels; 5. Diminished approximation of the corresponding portions of joints; 6. Diminished secretion of urine, as an effect of the increased evaporation. The observations on increased atmospheric pressure have been made in Tabarié's air-compressing apparatus, as it is used for therapeutic purposes at Nice, Montpellier, and other places, under the name "bain d'air comprimé." The author's inferences are based on researches made at Nice on himself and four other male individuals. For the description of the apparatus we refer to the essay itself. The experiments were made on eight successive days, between the hours of 12 at noon and 2 P.M., before the principal meal, the mean temperature being 11° Cent. (51.8° Fah.), the atmospheric pressure in the apparatus amounting to 1 atmospheres (925-04 millimetres mercury). The effects of the compressed air were: 1. A decided decrease in the frequency of pulsation; the greatest decrease being 18 beats per minute, the average 10 beats. 2. Dimination of the number of respiratory movements, amounting in the mean to 1.1 per minute. The influence, as well on the pulse, as also on the respiration, lasted beyond the time of the experiment; it seemed to be greater where the frequency of pulse and respiratory movements were morbidly increased. 3. Diminished evaporation from the surface of the skin and lungs. 4. Increased A millimetre 0.03937 inch, or 0.47 line. |