[Immunochemical study of specific "pregnancy protein" during mammalian ontogenesis]

beta1-globulins were found in the rats and guinea pigs in the extracts of placenta during the first term of pregnancy in one third of cases and beginning from the second term in all cases; they were not found in the other organs. These proteins were also present in the blood serum of pregnant rats, guinea pigs, foetuses and in the amniotic fluid, their concentration being much higher than in the placenta.