In the larynx the mucous membrane is inflamed and swollen, and a fibrinous exudation is thrown out between the basement membrane and the epithelial covering. This on examination can be separated into layers con sisting, according to Rindfleisch, of alternating strata of corpuscular ele ments (leucocytes) and of fibrin. The superficial epithelial layer very quickly disappears. The micrococci, which are found in immense numbers in the false membrane, have been already referred to. According to Senator, these organisms are common to all forms of stomatitis, and are probably identical with the spores of the leptothrix buccalis.
The consistence of the false membrane varies in different cases. It is often tough and tenacious, especially in the air-passages ; but sometimes is very soft and pultaceous. The latter condition is common when the false membrane occupies the pharynx in cases accompanied by severe constitu tional symptoms and great bodily prostration. The more usual seats of the false membrane are the tonsils, uvula, soft palate and back of the pharynx ; the nasal passages ; the larynx and trachea. Less commonly it is found on the conjunctiva ; at the borders of the anus, and in girls of the vagina. Sometimes it appears on wounds of the skin. The mucous mem brane is usually, as has been said, congested and swollen. It is very irritable and bleeds easily. Sometimes there is superficial ulceration, and in rare cases the ulceration extends deeply, and sloughing of the tissues may occur. Small ulcerations about the edges of the glottis are especially common in cases where the inflammation occupies the larynx. The cervical glands are swollen from rapid proliferation of small round cells, and the surrounding tissues are infiltrated with serum containing scattered pus-cells.
Besides these local pathological changes, other organs of the body are often affected. Thus : The lungs may be the seat of lobular pneumonia or collapse ; and the air-passages are sometimes lined with false membrane as far as their smaller branches.
The heart, although itself showing no signs of disease, may have its right ventricle filled with a colourless ante-mortem clot which extends into the ventricle. It is sometimes stated that the lining membrane may be the seat of endocarditis ; but Parrot asserts that he has never met with endo carditis in a case of fatal diphtheria. He believes that the beading else where described, which is almost a natural condition in many young infants, has been mistaken for the result of inflammation. Pericarditis,
however, is occasionally present ; and in a few instances a granular degen eration of the heart-walls has been observed. This degeneration is con sidered by Leyden, of Berlin, to be of an inflammatory character. It consists in a multiplication of the intermuscular nuclei which atrophy and form spots of degeneration. At the same time the muscular fibres undergo fatty degeneration. As a consequence of these changes the heart-walls become softer in consistence ; extravasations of blood take place into them ; and their cavities are dilated.
The kidneys may be enlarged and pale, with more or less granular deposit in the renal cells. The cells themselves are often detached so as to block up the tubes. They are mixed with hyaline casts.
Besides the above changes, there may be extravasation of blood into the various organs and beneath the mucous and serous surfaces. This occurs in the malignant form of other varieties of acute specific disease. On account of the frequent occurrence of paralysis during convalescence from diphtheria, the nervous system has been carefully examined for signs of degeneration. Charcot and Vulpian were the first to discover indications of pathological change. In the year 1862 these observers detected granular degeneration of nerves and muscles of the soft palate. In the motor nerves of this part the tubules were emptied of their medullary substance, and their neurilemma contained many granular cells. Oertel, in 1871, found many extravasations in the substance of the brain, spinal cord, and spinal nerves in a case where death had occurred from diphtheritic paralysis with general atrophy of muscle. Similar extravasations have been found by Buhl. In addition, this observer noticed the nerves to be thickened at their roots, and their sheaths to be filled with hypertrophied lymphoid cells and nuclei. Dejerine, in five cases of death in children from diph theritic paralysis, found in each instance changes strictly limited to the nerves supplying the paralysed parts. These changes consisted in a degen eration of the anterior roots similar to that which takes place in the distal end of a nerve after section. He attributes the degeneration to changes in the gray matter of the anterior cornua.