serum show any decomposition, when mixed with the serum of impregnated individuals. Had that been the case, then a very simple method for the diagnosis of pregnancy would have been found.
From the experience we have already gained, we may venture to say that the behaviour of blood serum towards coagulated placental tissue, or to placenta peptone, enables us to diagnose a state of pregnancy in the clearest possible way; or, expressed more correctly, to decide whether a placenta is in existence which is still in communication with the organism of the mother. A limitation is only necessary, because the defensive ferments can still be traced for a certain time after the expulsion of the placenta. For the practical sero-diagnosis of pregnancy this circumstance is of little importance, because the case under observation can be examined clinically. Normal non-pregnant individuals do not show any disintegration of the placental tissue.
We now had to decide the extremely important question, whether defensive ferments of a more general nature appear, when the organism contains other substances that are out of harmony with the plasma. This problem may be precisely expressed in the following manner: Does the serum of individuals, who suffer from infectious diseases, or from carcinoma, or who exhibit a disease of any other kind, decompose placental tissue? A priori, one was driven
