The commencement and duration of haemolysis and the length of time the erythrocytes remain intact in engorged virgin and fertilized females and in male Ornithodoros savignyi were investigated by means of red cell antigens.
There were no differences between fertilized and unfertilized females, haemolytic tests were possible in both groups up to 120 h after engorgement.
In the male group haemolytic tests were possible only up to 24 h after engorgement.
In both female groups inhibition of the in vitro haemolysis could be observed until the fifth day, after feeding on a calf with erythrocyte mosaicism, indicating the loss or masking of antigens due to the damage of cell walls.
The authors wish to thank Dr G. Theiler for her interest and advice during this work.