The Permeability of the Placenta of the White Rat to a Specific Hemolysin.

In view of the controversy upon placental permeability, the following experiments were undertaken to keep the animal under observation for a longer period than has heretofore been done, and to test placental permeability by means of a definite indicator (in this case immune serum hemolysin against guinea pig corpuscles). The white rat was used as it has been shown (Nicholas, 1925,1 19262) that this animal is capable of withstanding the shock incident to the necessary surgical procedure without subsequent abortion. Frequent injections could, therefore, be made into the foetus, and its condition followed through frequent observations.Specific immune serum hemolysins were prepared by the following method: 3 cc. of a 50 per cent suspension of washed guinea pig corpuscles were injected intraperitoneally twice a week for 3 weeks; the animals were not injected during the succeeding 10 days. The second series of injections was begun at the end of this period, twice a week for 3 weeks, consisting of a 60 per cent ...