STANDARDIZATION OF THE PRECIPITIN TECHNIQUE AND ITS APPLICATION TO STUDIES OF RELATIONSHIPS IN MAMMALS, BIRDS AND REPTILES

¹ From the Department of Zoölogy, University of Wisconsin, Madison, Wisconsin

1. Antibodies were produced in rabbits by injecting very small quantities of serum proteins of mammals, birds and reptiles.

2. Antisera produced by injection of a minimum quantity of antigen were the most specific as determined by the "ring" method.

3. Occasionally the serum proteins of such closely related animals as ox and sheep or gray squirrel and red squirrel could be distinguished.

4. Antiserum dilutions as low as 1 : 3 at times eliminated the heterologous reaction.

5. The "ring" appeared in the homologous and very closely related protein solutions earlier than in the more distantly related ones when incubated at temperatures of 37° ± 1° C.

6. It was not possible to distinguish between the buffalo and ox serum proteins or between the goat and sheep serum proteins.

7. Serological relationship studies of birds and reptiles seem feasible.

8. The procedures have not been entirely new but the necessity for uniformity and standardization of methods has been emphasized.