Separation of antigens by immunological specificity. 2. Release of antigen and antibody from their complexes by aqueous carbon dioxide.

of serological precipitates can be obtained by using a number of cells. 3. In this manner individual antigen-antibody complexes have been isolated with 5% or less contamination with the extraneous complex from the reaction of: (a) mixtures of fluorescent ovalbumin and haemoglobin and their mixed antibodies; (b) mixtures of fluorescent ovalbumin and 13I-labelled human serum albumin and their mixed antibodies. In the fluorescent ovalbumin-haemoglobin system the recoveries in the two precipitates of fluorescent ovalbumin, its antibody, haemoglobin and its antibody were satisfactory, namely 37, 10, 15 and 23% respectively of the original reactants. In the second system, the recoveries of 131Ilabelled human serum albumin and ovalbumin antibody were also satisfactory (approx. 25 and 22% respectively), but the recoveries of human serum albumin antibody and fluorescent ovalbumin were low (3 and 6% respectively). We are indebted to Mr J. F. H. Peel for help in designing the diffusion cell and toMrV. M. O. Longyear,MrsM. Restall and Mr W. Brent for excellent technical assistance. REFERENCES