We have thus seen while cancer is very widely distributed over the globe it is present in varying degrees of severity in different localities, and careful analysis shows that the disease affects different classes of persons with unlike severity. All these statistical studies and observations serve to confirm the statement made earlier that cancer is a disease of so-called civilization, and that it has increased in proportion as human beings have come under the influence of wealth, and consequent luxury and overindulgence, with bodily inactivity; all these elements lead to a disturbed metabolism, which as we shall see later, is, at least, a contributing cause to the deviation from normal of some of the cellular elements of the body. It also appears that some of these metabolic shortcomings have to do with a disturbed nitrogenous balance, which is due to the constantly increased consumption of meat. In 1909 the meat consumption in the United States had reached the high figure of 172 pounds per capita, as I learned recently from Washington, a far greater amount than in England, 130 pounds, as already stated; and with this steady increase in the use of nitrogenous food cancer has also increased by leaps and bounds in both countries. LECTURE III METABOLISM OF CANCER In the first lecture we saw that cancer was an alteration of the normal cells of the body, whereby they take on a malignant action and continue to do so, destroying contiguous tissues and leading to a lowered vitality, with an apparent poisoning of the system, which finally causes death. As the cells of various organs furnish different secretions, which in health contribute to proper metabolism, resulting in growth or maintenance of the tissues, so these disordered cells are believed to secrete a toxic substance, or malignant hormone, which has a prejudicial action on the body, and hæmolytic action on the blood, as has been brought out pretty clearly by Troisier and others. We saw that as yet the definite cause had not been determined, why at some period certain cells take on the action which we call cancer, nor why they persist in their destructive course. Long continued and abundant laboratory and clinical research have about decided certain questions negatively in regard to its etiology, so that in a measure the field is cleared for the study of some of the possible basic causes of the disease in question. Thus, all are pretty well agreed that cancer is _not_ contagious or infectious, that it is _not_ caused by a micro-organism or parasite, that it is _not_ wholly due to local injury, that it does _not_ appertain to any particular occupation, that it is _not_ hereditary to any great degree, that it does _not_ especially belong to or affect any particular sex, race or class of persons, _nor_ is it confined to any location or section of the earth, and that it is _not_ wholly a disease of older age.