Abstract
No method of preparing bacterial antigens for complement deviation can be regarded as wholly satisfactory until it offers a preparation in which the whole content of the complement deviating principles of the bacterial cell is rendered available and in which, at the same time, no substances occur that tend to interfere with the specific complement deviation reaction. The availability of the antigenic substances for the complementdeviation reaction depends; first, on their freedom in solution or suspension, and secondly, on the physical state in which they occur. While suspensions of whole bacteria have been used as antigen, it is most probable that their antigenic properties are to be attributed to a partial disintegration and extraction of the bacteria, for it is difficult to see how substances within the unbroken cell membrane could be available for 1eaction with colloidal substances in the serum, attributing, as we must by analogy, only semipermeable properties to the cell membrane.
