“Stable and detachable agglutinogen of typhoid bacilli”

By heating an emulsion of typhoid bacilli to 72° C. for half an hour a detachable agglutinin may be separated from the bacilli. This may be obtained in the filtrate on passage through a Berkefeld filter. Rabbits, which have been inoculated on the one hand by this filtrate and on the other by the heated bacilli, which have been thoroughly washed, show specific differences in their serums, as regards agglutination. The animal inoculated with the washed bacilli or stable agglutinin, produces a serum which agglutinates normal typhoid bacilli very slowly and with the formation of fine clumps. In contrast to this, the filtrate containing only detachable agglutinin gives rise to serum which clumps normal typhoid bacilli rapidly and with the formation of large flocculi.

Absorption experiments show, furthermore, that the s or stable agglutinin and the d or detachable agglutinin are distinct in character, for the heated and washed bacilli absorb nothing from the filtrate serum, but absorb all the agglutinin for normal typhoid bacilli from the bacillus serum. On the other hand the filtrate absorbs nothing from the bacillus serum, but takes up all the agglutinin from the filtrate serum.

It has also been determined that the substance in typhoid bacilli which gives rise to precipitins for filtrates of typhoid cultures is split off from the bacilli, together with the detachable agglutinums.

The possibility, further, suggests itself that the d agglutinin and the precipitin in a typhoid serum are identical.