The meningococcus, like some other pathogenic species, varies in its agglutination in immune serum, some strains being readily agglutinable while others agglutinate with difficulty in their homologous serum as well as in heterologous serums. The different strains appear to vary also in their action as antigens. In order to secure representative strains, therefore, it was thought necessary to consider the antigenic action as well as the agglutinability of the cultures.
We consider themost importantcontribution reported in this paper the fact that Treponema pallidum can be cultivated in fluid media, without the addition of agar, together with tissues sterilized by heat. This forms an excellent method of obtaining mass cultures for luetin preparation and immunological experimentation. We may add that while the tissue varieties employed have all stongly favored the growth of the treponemata, we have noticed especially active and motile cultures when lung and suprarenal tissues were employed.