Probably no influence is more potent in the domain of the etiology of disease than the various toxic processes. Closely related with these, and of scarcely less importance are the infectious processes. The latter are necessarily of extrinsic origin; the former may be also intrinsic. Infectious processes arise necessarily from the activity of micro-organisms, and these are invariably derived from without. Poisonous substances, however, not only may be derived from like sources, but they may also be generated within the body—for instance, on the one hand, alcohol, lead, mercury, opium, strychnin, etc., and on the other hand the toxic substances responsible for the manifestations of uremia, of diabetic coma, etc. Intoxication may further result through the activity of substances generated by infecting bacteria; from failure in the activity of certain glandular organs, as of the thyroid in myxedema, of the adrenals in Addison's disease, of the pituitary in acromegaly, of