The Application of the Reaction of Agglutination to the Pneumococcus

Owing to unavoidable circumstances only a limited amount of time was available for the work on agglutination. The foregoing report is therefore preliminary only and the following conclusions are provisionally offered: I. Pneumococci by reason of their agglutinating properties exhibit a tendency to separate into numerous groups similar to streptococci. II. Pneumococcus mucosus forms a distinct and consistent variety. The production by it of common agglutinins for some pneumococci and the resistance of the agglutinins produced by it to absorption by the streptococcus indicate a nearer relation to the former than to the latter organism. III. The agglutinating substances in the serum of immunized animals were demonstrated by absorption tests to consist of specific and group agglutinins in cases where the agglutinins were sufficiently developed to make use of this method. IV. The pneumococci seem to show marked differences in their ability to undergo agglutination. V. There was considerable uniformity of reaction of the various strains in low dilutions, but this uniformity is not continued as the animal becomes more highly immunized. VI. At present it is not possible to establish a definite relation between the agglutination reaction and the other characteristics of the pneumococcus excepting in the case of the Pneumococcus mucosus.