METASTASES form a very considerable and important element in inoperable and recurrent cancer, and we will briefly consider these. They occur mainly through three channels: 1. The lymphatic system; 2. The venous system; and 3. The arterial system. The permeation theory of Handley relates to direct extension laterally through lymphatic spaces, and belongs to the first mentioned means of extension. It is also believed that metastases may be formed in the peritoneal cavity, and likewise in the pleural cavity, by direct contact of cancer cells or pieces of malignant tissue which have gained access to those cavities and have been carried down by gravity and movement of viscera. They then become engrafted on healthy tissue and form metastases there. While holding firmly to the belief that the original cancerous growth and other foci of disease are developed from a vicious state of the blood current, there seems to be no reason for doubting that the disease may also be extended in the manner above indicated. Although cancer material cannot be inoculated from one person to another, or from a human being to animals, nor from one species of animal to another, experience and observation show that the malignant process can be transferred from one organ or structure of the same individual to another part or structure, whether there has been a surgical operation or not. The lymphatic system is apparently the first means for the spread of the malignant process, and all are familiar with the lymph nodes seen in the neighborhood of cancerous masses. It is supposed that these are caused by the lodgment of detached cells which have taken on the abnormal reproductive action which characterizes cancer. As with other foreign bodies, pus cocci, etc., the minute lymphatic glands seek to arrest their passage into the circulation, and it is probable that some of them are destroyed there, for the single enlarged gland will often remain for a long time as the only manifestation of metastasis. In many cases, where the original cancer has disappeared under dietary and medicinal treatment, the enlarged glands also disappear, as I have seen many times. When the disease is unchecked, however, the glands fail in their endeavor to protect the system and continue to enlarge one after another along the line of the lymphatics, and the lymph stream then carries certain cancer elements through the thoracic duct into the venous circulation; thence they reach distant parts of the body, through the arterial system, and, being lodged in capillaries, a more or less general carcinosis results. Cancer elements can also proliferate along lymphatic tracts, and, furthermore, they may enter the venous and arterial systems directly by the invasion of a malignant growth.