When salivation has been induced, serum is poured out, and the texture of the gums is loosened and rendered spongy. When lymph is effused upon the iris, the action of mercury loosens its adhesions, and dissolves its connexions; it cannot, therefore, be supposed that its effect upon the system should render the union of divided vessels stronger, or the newly-formed adhesions in wounds, firmer. The cases in which purulent deposits usually form, indicate a debilitated state of constitution. They are of much more frequent occurrence in large towns than in the country, and in hospital than in private practice. The depressing influences which give rise to erysipelas, or puerperal fever, will also predispose to the formation of these abscesses; and as scanty diet, loss of blood, debilitating surgical operations, and over-crowded rooms, have been found among the causes of the former, so may they be looked upon as favouring the production of the latter. The Treatment of Inflammation of the Veins, in which purulent deposits frequently originate, is thus spoken of, after matured observation: "All the experience that I have had on the subject, would lead me to believe that, like erysipelas, it has its origin in a low asthenic state of the system, and that those persons are especially liable to it, who have been much lowered by hæmorrhage at the time of an operation, or by too scanty a diet afterwards. An operation is a shock upon the system, making a great demand upon the vital powers. The effects of this shock are often much aggravated by loss of blood, and a very scanty diet actually makes the patient more liable to some kinds of inflammation. Our mode of practice ought to be rather to sustain his powers by allowing him wholesome nourishment, and not to add to the influence of the other depressing causes, the still worse one of starvation."[42] [42] BRODIE (Sir B. C.) Medical Gazette, vol. xxxvii, p. 642. The lowering influence of mercury may be considered in a similar way. There can be little doubt that while, on the one hand, it favours the absorption of vitiated fluids, it may, on the other, render the system less able to resist the injurious consequences which they produce. As many circumstances, besides mere debility, tend to depress the vital powers, so tonic medicines, and a generous diet, must not be looked upon as the only preventive modes of treatment. Each case that occurs in practice may present some peculiarity; in one case, the patient will be found to have previously suffered from diabetes; in another, from disease of the spleen; and in a third, from organic disease of the kidney; and, in each of these, a peculiar mode of treatment may be required.