To the patient, who has been led into the path of health, it will, as is its purpose, give such instructions as will enable him to see his condition plainly. _He will then be able the more effectively to follow the instructions of the physician, and--what is of equal importance--to inform him correctly in regard to his own observations of his condition and the changes brought about by the treatment._ There is another point that I wish to mention here at the outset. Disease, although reduced to its last analysis under this system, is never so simple that it can be determined as the degeneration of one tissue exclusively. The unity of the body, the close connection of the various tissues, and the gradual transition from one into another, make it impossible to draw the lines as sharply and distinctly as between chemical elements. For the sake of classification we make the degeneration of a certain tissue the distinguishing element between various forms of disease. Let us not forget, however, that this does not mean more than the _degeneration of the main tissue_ which is affected by this particular complaint, while the same is also characterized by simultaneous degeneration of one or more of the other tissues, only to a lesser degree. It is, therefore, not inconsistent if, in giving the more detailed description thereof, several tissues are mentioned as being degenerated, and not only the one particular tissue from which the class derives its name. I. DEGENERATION OF THE PLASMO TISSUE. _Anaemia, Chlorosis, Pernicious Anaemia. A. Scrofulosis. B. Tuberculosis. C. Syphilis. D. Cancer._ To many who are unfamiliar with the results of modern research, and even to many physicians of the old school of medicine, the family of disease forms, as enumerated above, will look somewhat formidable. It comprises the most disastrous plagues of mankind,--plagues for which cures have been so frantically sought with such an ominous lack of results. It thus constitutes one of the most practical revelations of the biological method of research to positively proclaim that the common cause of these manifestly so different constitutional diseases is one and the same. That this fact was not recognized long ago is the reason they have been pronounced incurable by so many physicians who, by poisoning symptoms, established only a semblance of cure, until biological study led to the recognition of the truth. It discovered that all of these constitutional diseases are essentially blood defects and degenerations, resulting in the destruction of the body tissue in general,--the necessary and logical consequence of an imperfect condition of the blood. So there is a ray of hope for humanity breaking through the night of despair; that is, that its worst foes can be made to disappear in due time by attack directed at their common root.