IS CANCER OF INFECTIOUS NATURE?

Malignant new growths are found in various classes of the animal kingdom and seemingly also in plants. Although cancers were recognized and treated surgically by Galen, the modern conception arose only with the discoveries of Virchow in 1853 and the theory of Cohnheim in 1867. Since that time innumerable workers have approached the problem of cancer from every angle. The clinical symptoms, the gross and microscopic anatomy, the rate and manner of growth, the production of metastases, the chemical changes produced, and their biologic aspects in general have been thoroughly investigated. Little concerning many of these phases remains to be discovered, but of their cause little indeed is known. The theory of Cohnheim remained the most tenable until recent years. At various times, bodies have been found in cancer which were interpreted as protozoa, bacteria or yeasts. The failure to cultivate these bodies, together with the demonstration that they were