Abstract
A method is described for the quantitative extraction of posterior pituitary antidiuretic substance from blood with which it has been mixed in vitro and in vivo for experimental purposes. With this procedure, it is found that a similarly extractable active substance may be detected as a normal constituent of dog and human blood. The data obtained from the blood of normal pregnancies and several cases of early toxemia, do not indicate any causal relationship between the presence of this substance in the circulating blood and the early symptoms (hypertension, edema, albuminuria) of the toxemia of pregnancy.