pregnancy, were published. Pregnancy is a condition which allows of no misinterpretation. In almost every case the clinical diagnosis can be compared, with absolute certainty, with the result of the serological diagnosis. The actual diagnosis either corresponds with the former, or it does not. These clear conditions, however, are not presented by the other morbid processes. A certain disease may be accompanied by all kinds of other disturbances of the functions of the organ. Very seldom are we faced with the presence of "pure" disease. Therefore, we are bound to conclude that only the worker in a hospital is in a position to judge, to what extent serological investigations can be applied for testing the functions of an organ. In this case two aims have to be distinguished. The serological diagnosis can, in many cases, widen our understanding of the disturbances occurring in a given disease. We gain an insight into long suspected functional troubles of certain organs, or discover that others, which had never been thought of, regularly produce disturbances in a certain disease. It is an entirely different question to ask whether the serological diagnosis of an organ can be applied to differential diagnosis, i.e., whether we are entitled to accord a preference to this, as against any other, method.
Many years may be required before the question of the practical value of the methods worked out can
