The chemistry of cancer has been studied in most varied directions, and the literature relating thereto is very voluminous and can be hardly more than alluded to here. It is unfortunate, however, that most of the researches have been made in connection with patients who have advanced cancer, and very commonly with the disease affecting internal organs, which of itself interferes very greatly with their function, and so causes many of the perturbations of metabolism observed. What is needed are researches in regard to the metabolism of patients before the development of the disease, or in its earlier stages, before it has exerted its injurious effects on the system, in order to learn of the causes which lead up to and induce the wrong action of the cellular elements, whose invasion and malignant action subsequently become so serious. It is quite impossible in these lectures to enter at all fully upon the various bio-chemical studies which have been carried on in regard to cancer, but brief mention will be shortly made of some of the salient points. Not only has the structure of carcinomatous tissue been examined chemically, but the blood and urine have been submitted to most painstaking investigation, and metabolism in general has been studied in almost all possible directions, in the search for the cause of cancer; and yet, as Beebe says, “no phase of metabolism has been described in cancer which does not have a counterpart in non-cancerous conditions.” But, as previously mentioned, all these observations and studies have been largely made upon advanced cancer cases, when the system has already felt the unsettling and depressing effect of what is probably an injurious secretion from the deranged and actively proliferating cells of the cancerous mass. In a later lecture we will consider some of these matters in so far as they have relation to the dietetic and medical treatment of cancer. The essence of our study thus far has been, that in every instance what is called malignant disease is but an aberrant action of originally normal body cells. That, as normal cells find their nutriment in the circulating plasma, so some pathological change in this latter causes them to take on abnormal action, and they no longer develop homologous cells, capable of forming normal tissue, but heterologous elements which have a natural tendency to disintegrate or break down, and exert a destructive influence on adjoining cells of any kind; and in this process they secrete a hormone which is prejudicial to the system and tends to destroy life. In later lectures we shall endeavor to understand this more perfectly, and consider some of the elements in life which tend towards the production and arrest of cancer. LECTURE II FREQUENCY AND GEOGRAPHICAL DISTRIBUTION OF CANCER