5. The Presence in the Blood of an Excess of Fibrin.—In many forms of inflammation the blood contains an increased quantity of fibrin. In acute rheumatism this excess is specially marked.
Fibrin is a product of tissue waste—an excrementitious rather than a nutrient compound. The evidence of this is that it accumulates during fasting and during many ailments accompanied by increased waste. It exists also in increased quantity in the blood after fatigu ing exercise ; and Brown-S4quard has shown that the more a muscle is exercised by galvanism the more fibrin does the blood issuing from it contain. There can be ILO reasonable doubt that fibrin is a product of the retrograde metamorphosis of nitrogenous tissue. We know that inflammation causes increased metamorphosis of the tissue in which it occurs. We know that rheumatism consists in inflammation of the tissues of the motor apparatus. We know that these tissues are the chief source of the fibrin of the blood. We know, therefore, that rheumatic inflammation must be accompanied by increased for mation of fibrin. The presence in the blood of an excess of fibrin during the course of acute rheumatism is thus a necessary result of the morbid action which constitutes the characteristic feature of the disease. It results from increased metamorphosis of the nitrogeneous elements of muscle just as excess of lactic acid results from increased metamorphosis of the non-nitrogenous.
6. The Presence in the Blood of an Excess of Lactic Acid.—This, one of the characteristic phenomena of acute rheumatism, has already been considered.
It has been shown that lactic acid is a normal product of the retrograde metamorphosis of muscular tissue; that its formation in excess during muscular exercise results from increased wear and tear of the tissues of the motor apparatus; and that its excessive forma tion in acute rheumatism is due to the same cause, only differently induced. In the one case, the increased metamorphosis results from exaltation of a natural function; in the other, it is a consequence of a pathological process, induced by the action of the rhemnatic poison, and leading to excessive formation of lactic acid, in the manner al ready explained.
The argument may be briefly summed up as follows : Rheumatism is essentially a disease of the motor-apparatus of the body, Acute rheumatism essentially consists in acute inflammation of the most active parts of that apparatus. The tissues chiefly in volved are the muscles and fibrous textures. The rheumatic process must, therefore be accompanied by increased metabolism of these textures. White fibrous tissue contains only nitrogenous material ; muscle contains both nitrogenous and non-nitrogenous. Its non nitrogenous material is glucose ; and it is from this that lactic acid is formed. The difficulty has been to account for the increased meta morphosis of glucose as evidenced by the increased formation of lactic acid. The view which has been advanced as to the nature of the rheumatic process disposes of this difficulty. That poison is repro duced in the muscles and fibrous textures. By seizing on the con stituent elements of these, and appropriating them in its growth and reproduction, it causes in these textures the same increased metabo lism that naturally results from increased functional activity; in doing this it necessarily causes increased formation of their ordinary meta bolic products ; one of the metabolic products of muscle is lactic acid.
Increased formation of lactic acid is, therefore, one of the results of the rheumatic process; and this increased formation is kept up during the continuance of that process. It results from increased metamorphosis of the non-nitrogenous elements of just as in creased formation of fibrin results from increased metamorphosis of the nitrogenous.
7. The Occurrence of Profuse Perspiration& —Abnormally free action of the skin is a characteristic of acute rheumatism. As a rule, the more acute the case and the more intense the joint inflammation the more free is this action. The perspiration has an acid reaction, and continues during the whole course of the acute symptoms. By some these sweats have been regarded as exhausting and debilitating, and, therefore, as injurious. By others they have been looked upon as salutary. When two such antagonistic opinions are held we may safely infer that neither expresses the whole truth. In some cir cumstances profuse perspiration is both evidence of weakness and a cause of increasing debility. In others it is unquestionably salutary, and seems to be the means by which certain disturbances of the system are brought to an end. In rheumatic fever it cannot be said to have either effect. There is no evidence that it causes such debility as results from the night sweats of phthisis ; but those who study it in connection with these sweats will naturally draw the inference that it is weakening. There is no evidence that it pro duces the salutary effects which are noted in connection with the critical perspirations of pneumonia and other acute febrile ailments; but those who study it in connection with these critical sweats will naturally conclude that it is salutary. All cases of phthisis do not have night sweats; they are among the unfavorable symptoms of some cases. All cases of pneumonia do not have critical perspira tions; they are among the favorable symptoms of some cases. But all cases of acute rheumatism have acid sweats, and have them not occasionally or at one period only, but continuously through the whole course of the fully developed disease. There is no evidence that they exercise a favorable influence on the course of the ailment, there is no evidence that they influence it unfavorably. The acid sweats of acute rheumatism are altogether peculiar, altogether differ ent from those noted in connection with exhausting maladies and the crises of acute febrile ailments. They constitute one of the essential symptoms of the disease—one of the invariable results of the action of the rheumatic poison. How are they produced? The blood in acute rheumatism contains an excess of lactic acid. This it is which gives to the perspiration its acid reaction and odor. As this acid has been regarded by many as the cause of rheumatism its excretion by the skin has naturally been looked upon as a thing to be desired, and this is the foundation for the belief that the pro fuse perspiration of acute rheumatism is salutary. For so, on this view of the matter, it ought to be. The probability is a hypothetical one, however, which is not supported by fact; for practically we find that the most profuse perspirations afford no relief to the pain. In fact the pain is, as a rule, more severe in cases in which the sweating is most free.