As is well known, before the discovery of vaccination, persons were _inoculated_ with the small-pox, because it was found that the disease could _be thus rendered_ comparatively harmless; whilst, if it was taken naturally, as it was termed, it was always serious, and too frequently extremely fatal. The preparation for inoculation consisted of _measures addressed to the digestive organs_. Now the effect may be judged of by this fact: Inoculation was at first violently opposed; and, in reply to the alleged safety of it, an opponent wrote to prove that _one_ in _one_ hundred and eighty-two had died of it. I wish we could say so of many other diseases. That such persons had, nevertheless, the genuine malady, was proved by the fact they were capable of infecting others (unprepared) with the disease in its most malignant form. But our notions of the mode in which the laws of the animal economy deal with injurious influences of this kind, are mischievously conventional. What quantities, for example, of mercury, in its different forms, have been administered in almost all diseases; and yet unquestionably there is a great deal of false reasoning in regard to this poison. Effects are attributed to it _as mercury_, which only belong to it in _its general character of an injurious agent_. All the (so-called) specific effects of it, most of which are become popularly familiar, may occur without any mercury at all. We have seen them induced by aloes, by scammony; and in a case where no medicine had been given, and where the only detectable poison was one which was to be sure bad enough, an enormously loaded liver. We are obliged to say but little here in connection with this subject. Abernethy's cases were very important in relation to the influence of the digestive organs, although he did not see the generalization to which, as it appears to us, they help to conduct the pathologist. The subject is too extensive for discussion here. We will attempt something of a popular view of it, when we endeavour to explain the fallacy to which we have already referred. Abernethy next adduces various illustrations from cases of other diseases; as indurations, tumours, carbuncles, scrofulous affections, and others; in proof of the dependence of a "numerous and dissimilar progeny" of so-called local diseases, on that "fruitful parent," disorder of the digestive organs. Of one of the most interesting and remarkable cases of tumour, Mr. Abernethy did not live to see the termination. It was of a lady who consulted him previous to the proposed infliction of an operation. She had been recommended by my father, in the country, to consult Abernethy before submitting to it; because he disapproved of it, as did Abernethy—not because they doubted of the nature of the disease, but because it was not confined to the part on which it was proposed to operate.