1. The hereditary transmission of the rheumatic tendency neces sarily involves the idea of a constitutional, not a local, malady. It means that a certain diathesis, or particular state of the body, pre disposing to rheumatism, is handed down from father to sou. But such transmission can take place only in connection with constitu tional ailments. We talk of a gouty, a rheumatic, a strumous, a can cerous diathesis ; but never of a pleuritic, a peritonitic, or a nephritic oue.
2. The tendency to attack those of a particular age is a feature which is noted specially in connection with diseases owning a con stitutional origin; and which is manifested in rheumatism, as it is in struma, gout, cancer, etc.
3. The liability to repeated attacks in the same individual equally points to constitutional predisposition.
4. The fact that many joints suffer simultaneously or in succes sion, points to a generally operating internal and constitutional cause ; for it is most improbable that an external and local cause could habit ually produce inflammation in so many different parts as suffer during a rheumatic attack independently of a constitutional predisposition.
5. The tendency to heart affection can be explained only on the view that the true cause of the inflammation exists in the system. That cold and damp might give rise to an endo- or pericarditis is possible; but that the occurrence of such inflammation in thirty-three per cent. of the cases of acute rheumatism can be due to other than a generally acting constitutional cause, is in the highest degree im probable.
6. The rarity of suppuration, no matter how intense and pro longed the inflammation, indicates that rheumatic is essentially dif ferent from ordinary inflammation. "I have often known acute rheumatism of the severest kind have the start of the remedy, full ten days or a fortnight, during which nothing whatever has been done for its relief; and when at length the remedy has been applied, it has been cured as easily and rapidly as I could promise myself that it would have been had I taken it in hand teu days or a fortnight sooner.
" Surely here is something remarkable enough to make us stop and think for a moment. An inflammation of the brain, the liver, or the lungs would not thus wait our pleasure, or our neglect, and be as curable ten days or a fortnight hence as it is to-day. For inflamma tion in these organs does not stand still. It is progressive from stage to stage, and each succeeding stage carries it further and further away from the remedy. But it is the very peculiarity of acute then ma tism that it does, in a certain sense, stand still. All its actions and movements are simply as forcible and rapid as possible, yet does it stand still. All its energy is expended upon one stage, and there is no apparent progression beyond it. A fortnight ago there was great heat, and nervous and vascular excitement, and great pain and swelling of the joints; and, to-clay, the heat, and nervous and vas cular excitement, and pain and swelling are exactly of the same amount as they were at first. There is uo more sign. of parts dis organized, or parts destroyed, now than then" (Latham).
7. Finally, the success of constitutional, and the futility of local, treatment complete the proof that in rheumatism we have to deal with an ailment which owns an internal and constitutional, and not an external and local, cause.
But though exposure to cold and wet are not per se the cause of acute rheumatism, there is ample evidence, the result of the accumu lated experience of all countries and all observers, that such exposure often acts the part of an aides and abettor in determining a rheu matic attack. It does not itself give rise to the disease, but it ren ders the systems of those liable to be affected by the special cause of acute rheumatism more susceptible to its action.
How it does so is one of the questions which have to be considered in connection with the different theories advanced as to the nature and mode of action of this special cause.