The statement of Virchow, “Omnis cellula e cellula,” that is, “where a cell arises there a cell must have previously existed, just as an animal can spring only from an animal and a plant from a plant,” forms the basis of all study on the genesis of cancer and all tumor formation; karyokinesis, or indirect nuclear or cell division, is at the bottom of all growth, both normal and malignant, and the two classes of growth differ only in their methods and activity. In healthy tissues cell proliferation and destruction proceed in an orderly manner, forming homologous structures, as when the hair and nails are constantly produced from newly formed cells at the root, and the result of this new growth is removed mechanically when the hair and nails are cut from time to time, or the hairs fall out. In the case of the skin the epidermal layers are pushed forward and finally exfoliated as useless epithelial débris. With the cells composing other, or internal structures, however, the process is different. For here each normal cell reproduces others of homologous structure, and the different parts of the system are thus kept in active service through anabolism, by means of which new cells are formed with renewed vitality, and the older, or effete cells are removed by catabolism; the elements of which they are composed are thus split up into their component parts, and carried off by the blood or lymph stream, and are then either discharged as effete substances or reutilized in the system, along physiological lines. Wakefield has pretty clearly shown that the developing cancer cell is the product of sub-catabolism, or a sub-oxygenation, induced by hyperacidity or oxidase deficiency in the surrounding medium of the blood plasma.