It is impossible to follow the course of >vater through the whole of the alimentary tract for the reason that, after leaving the stomach, it gradually becomes absorbed. We know, however, that it passes rapidly through the mouth, pharynx, and esophagus until it reaches the stomach, where it is retained for a considerable time, and that after leaving the stomach, there is no obstruction to its passage through the duodenum or other portions of the intestinal canal. The only important difference,

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... erefore, between the stomach and the mouth, pharynx, esophagus, or duodenum is in the greater length of time during which water is retained therein, and it is for this reason only, and not because lesions are present more frequently in the stomach than in other parts, that gastric cancers outnumber cancers of all other abdominal organs together. The attack of cancer falls on the pyloric region because it is the most common seat of gastric lesions, but inasmuch as there is good reason to believe that lesions of the buccal cavity and of the duodenum are more frequent than in the pyloric region, we can hardly doubt that, if the opportunities for exposure of lesions in all these parts to water were equal, cancers of the mouth and duodenum would then outnumber cancers of the pylorus. With regard to other parts of the alimentary system, our knowledge of lesions and of their exposure to water is insufficient to warrant our forming any conclusions. Nevertheless, if we believe that the principle of cooperation between lesions and water is true in the case of cancers of the mouth, stomach, and duodenum, we must also believe that it is true in the case of the intestines, peritoneum, liver, and other parts of the alimentary system lying beyond the range of observation. There is reason to think that cancer of the rectum is due, not to water which has passed through the alimentary canal, but to water deliberately applied in the course of the treatment for constipation and other affections. Probably no organ or part of equal size is so frequently the seat of affections tending to result in lesions as the lungs, but notwithstanding this, there are few parts or organs in which lesions are better protected from water, or which show less tendency to become cancerous. The lungs, however, are not peculiar in this respect, since a brief consideration of the facts of cancer incidence as a whole will show that, whereas the greater proportion of the risks from cancer are borne by parts and organs which are commonly exposed to water, there is, in all parts and organs protected from such exposure, a remarkable freedom from the disease. It would be difficult to find a better illustration of this than that which is supplied by a comparison of the facts of cancer incidence upon the lungs and upon the stomach. Lesions are present more frequently in the lungs than in the stomach, and if "chronic irritation," or airy other form of stimulus associated with their presence, were capable of causing cancer, we should certainly expect pulmonary cancers to outnumber gastric cancers. Since, however, the contrary is true, it is obvious that lesions acting alone cannot cause cancer, and it therefore becomes impossible to find a satisfactory explanation for the facts except on the ground that, whereas in the stomach exposure of lesions to water is almost continuous, the opportunity for such exposure can only arise in the lungs in the event of a rare accident. Cancer of the female generative system stands second in order of frequency to cancer of the alimentary organs, not because it is more exposed to injurious influences or to water than many other parts of the body, but because of the vulnerability of one point, namely the cervix uteri. In so far as cancer is concerned, the cervix uteri stands in the same relation to the female generative system as the pyloric region does to the alimentary system, that is to say, it is the point upon which nearly the whole weight of the disease is focussed. It seems reasonable, therefore, to believe that the principles of causation which were found to be applicable to the problems of cancer in the alimentary system, will also serve to explain cancer of the female generative organs with the same degree of consistency. The cervix uteri is, par excellence, the seat of inflammations, lacerations, ulcérations, erosions, and other lesions having a tendency to persist for months, or even years, and moreover, it is most favorabty situated for contact with any water which may happen to enter the genital passages.