The immune response of turtles to giant keyhole limpet hemocyanin was studied by means of the precipitation of I*-hemocyanin by antiserum. The pertinent findings were:
The 18 S protein constitutes 13 to 26% of the total normal serum protein in the turtle.
In an antibody response rapidly sedimenting antibody predominates for the first month and is gradually replaced by slowly sedimenting antibody.
The slowly sedimenting antibody activity as well as that of the rapidly sedimenting antibody activity is almost entirely destroyed by 2-mercaptoethanol treatment.
No anamnestic response occurred.
The precipitin reaction between turtle antibody and antigen remains, throughout the course of immunization, similar to a mammalian primary response in that it is greatly effected by dilution of the test system.