is a simple lesion or a source of paralysis, the difference in results being dependent upon a difference in the condition of different cells. This difference in the condition of the cell forms its predisposition. Previous to this, the old humoral theories which regarded the whole compound mass had held more or less sway in medical practice, and the recognition of diseases as local anomalies had made but slow progress. A few workers, from Vesal and Paracelsus down, had gradually given shape to the local theory, and Virchow claimed that his cellular pathology was a consistent carrying out of the principles they had established. In it the localization of disease was taken as a necessity, and its seat was fixed in the smallest composing element, or the cell. Therapeutics have also undergone important changes in the light of this theory, and under the guidance of experimental methods, and have become vastly more exact and efficient, and local in application. Thus far, Dr. Jacobi asserts, every new discovery of pathological facts has found a ready explanation by the cellular theory and its methods. "The changes worked in and by the white blood-cells, the transmutation of epithelial cells into benign results or malignant growths, the influence, real or imaginary, worked by bacteria, have but strengthened its plausibility."
An antagonism to Virchow has apparently been assumed by some of the partisans of the bacterial theory of infectious diseases which has no real basis for existence. No discrepancy need exist between a theory which regards disease as a disorder of the cells and the one which finds in the bacteria an external agency provoking and promoting cell-disorder. The publication of an essay on parasitic plants, in the first volume of Virchow's "Pathology and Therapeutics," in 1854, shows that his attention had been directed to the subject even then. In 1856, also, a paper was published by him, in the "Archiv," on the botanical nature and classification of some forms of parasites to which an important part in nosology was to be attributed, on which occasion he invented and first used the term "mycosis," which has since been generally adopted. Brauell's papers on the bacterial parasite of anthrax, following up the researches of Davaine and Pollender, appeared in the eleventh and fourteenth volumes of the "Archiv," and were followed by numerous papers in that and other journals. Obermeier found the spirochœte in the blood of relapsing fever, in Virchow's hospital division, in 1873.
Virchow himself has said on this subject, in answer to an attack by his former pupil Klebs: "Vegetable and animal parasites are among the causes of disease. Their place is in etiology, and therefore it is easily conceived that, as Klebs expresses himself, they found no place in my cellular pathology. There it was not any more my domain to offer an extensive paper on parasites than it was to treat of traumatic injuries and corrosions. In my cellular pathology I meant to demonstrate the changes which take place in the elements of the