TRANSCRIBER'S NOTE Italic text is denoted by _underscores_. The 'Apothecary System' of measurement was used in the original text. The etext uses the following Unicode symbols: ℞ Prescription symbol ʒ Dram ℥ Ounce ℳ Scruple Roman numerals, and 'ss.' for 'half', are retained, so for example '℥iss.' indicates 'one and a half ounces'. Obvious typographical errors and punctuation errors have been corrected after careful comparison with other occurrences within the text and consultation of external sources. More detail can be found at the end of the book. THE LONDON MEDICAL GAZETTE, BEING A WEEKLY JOURNAL OF Medicine and the Collateral Sciences. SATURDAY, DECEMBER 27, 1828. PATHOLOGICAL ESSAYS ON SOME DISEASES OF THE HEART; _Being the Substance of Lectures delivered before the College of Physicians_, BY P. MERE LATHAM, M.D. Physician to St. Bartholomew's Hospital. [Continued from p. 7.] ESSAY II. _Morbid Anatomy of the Internal Lining Membrane of the Heart._ The membrane which lines the cavities of the heart is very liable to disease, but not equally so in every part. Where it is thin and transparent, and admits the colour and character of the muscular structure upon which it is spread to be seen through it, it is seldom found diseased; but where it is of a denser texture, either in itself or from an admixture of other structures, whether cellular or fibrous, with its own, it is frequently, and often exclusively diseased. This latter character of a denser texture belongs to it where it forms the tough white circles which surround the apertures of communication between the auricles and ventricles; also where it is reflected upon itself, and forms the loose duplicatures of membrane, which are given off, as it were, from the internal surface of the heart, either at the fibrous circles intermediate between the auricles and ventricles, constituting the tricuspid and the mitral valves, or at the commencement of the pulmonary artery and aorta, constituting the semilunar valves. It is remarkable how curiously disease is apt to limit itself to the spaces just pointed out. Of the fibrous circle between the auricle and ventricle, of the valves which originate from it, and of the tendinous cords which connect the valves with the carneæ columnæ, there will not be the smallest space free from disease; but the disease will abruptly stop where the tendinous cords cease and the carneæ columnæ begin[1]. The membrane, however, where it covers the fleshy columns of the heart, is not exempt from the possibility of disease: but when disease actually affects it, it has seldom originated there, but has generally spread from other parts of the same membrane, although (as we have just remarked) it is apt to stop short before it reaches this.