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July 19, 1902


JAMA. 1902;XXXIX(3):142. doi:10.1001/jama.1902.02480290026011

So long ago as 1891 Metchnikoff observed that pneumococci grown in the serum of immunized animals form long chains in place of diplococci. This was confirmed by a number of observers, and Bezancon and Griffon1 noted the occurrence of similar phenomena on the part of pneumococci added to the serum of patients with pneumonia, especially on or about the day of the crisis. This reaction, which is a form of agglutination, is best seen in mixtures in the test tube where a distinct precipitate forms. The addition of pneumococci to normal serum gives only a diffuse cloudiness. These authors found that the serum early loses the power of agglutination. Recently Neufeld2 has brought important additional observations upon this phase of the behavior of pneumococci. While normal serum does not materially alter the form or relation of pneumococci, 24 to 48 hour bouillon cultures mixed with equal parts immune