In regard to the real bio-chemistry of cancer, we are still greatly in the dark. Vast numbers of studies and researches have been made to determine the real character and nature of the bio-chemical changes which occur in cancerous tissue, and the mere recounting of the reported findings and theories elaborated from them would occupy far more time than can be profitably given in these lectures. Some have claimed very positive findings which account in a measure, at least, for the pathological conditions, while others, as Beebe, state that “the chemical study of tumors is in its infancy. We have scarcely proceeded far enough to know where the medical problems are, nor have methods now available been perfected to such an extent as to enable a decisive experiment to be made.” “No phase of metabolism,” says he, “has been described in cancer which does not have a counterpart in non-cancerous conditions. This applies to such questions as the nutritive relations between the cancer cells and the normal body tissue, to the nitrogenous balance, retention, elimination of sodium chloride, excretion of acetone, the relation of ammonia excretion, and a possible acidosis.” He adds, however, “Diet doubtless forms an important part in the growth of cancer, possibly even in the origin of the disease.” It is encouraging, therefore, to find that this able and careful laboratory investigator recognizes, in a measure, the basic cause of diet, toward which all evidence points so strongly, although the definite connection may not yet have been established by laboratory methods. In all our study in regard to the relation of diet to cancer it must be remembered that there are divers elements and agencies which combine to produce the many and various disordered conditions of the body, to which we give the names of different diseases, and that cancer is no exception to this general rule. For instance, in old-fashioned gout the patient may have consumed an excess of Port and Madeira wine for years before the system finally rebelled and acute gout resulted; and among the causes for the systemic reaction we know that frequently it is great mental strain or shock which has so disturbed metabolism that the wine was no longer tolerated. Much the same is true in regard to cancer and nitrogenous diet. And we will see later that mental disturbance and nerve strain or shock often seem to be causative elements; also that constipation, or intestinal stasis, is so common in cancer subjects that it must be looked upon as one of the contributing causes among others, to be mentioned later.