This constitution is more easily acted on by certain agents, particularly such as tend to induce inflammation, than healthy constitutions in the same circumstances. It would likewise appear, that, on the contrary, there are other agents which operate with more difficulty. It is in general observable, that scrophulous people are less easily affected with mercury. On a few, indeed, it operates readily; but, when we attend to the general habitude of these people, we must consider the aptitude of some individuals to assume the mercurial action to depend on some peculiarity of constitution, unconnected with the scrophulous condition. By the ancients, and many of the moderns, the pituita was considered as the cause of scrophula, producing tumefaction, by stagnating in the glands. When any of the bile became mixed with the pituita, then the inflammation was more violent, and the ulceration deeper. Some latter writers, convinced that a simple redundancy of any particular humour could not produce scrophula, had recourse to the supposition of an acrimony, which was productive of swelling and ulceration, and which might “taint the whole fluids of the body[85].” [85] Cullen’s First Lines, Vol. IV. Others attempted to explain this disease, upon the principle of debility existing in the whole body, but particularly in the lymphatic system[86]. This is an idea still more puerile than the doctrine of morbid humours, which, however unfounded, had several plausible arguments to support it, and which was incontrovertible until the laws of the animal economy were better understood. Simple debility never can give rise to the marks of the scrophulous constitution; it cannot produce ulcers of a nature and appearance so peculiar; neither can it explain why particular parts are more apt to be affected than others; because, if debility exist equally in every part of the absorbent system, then every part ought to be alike diseased; and if it exist only in particular parts, then it is necessary to point out some cause of this partial debility. We likewise frequently observe very great debility in this system, owing to general weakness, and yet no symptoms of scrophula appear in consequence. [86] Bell’s Treatise on Ulcers, p. 424.