I+om the D q m ' t n i e n t of Bacteriology and Immunology, Peiping Union MedicalCollege, Peiping.Since the existence of serological types among C. diphtherkz is well established's 2* ' the isolation of a cellular constituent responsible for type-specificity appears to be possible. Previous reports4? ' have shown that the polysaccharides of C. diphtheria in general are group specific being shared by members of distinct serological types. From this it may seem obvious that a cellular component other than the polysaccharide is responsible for type-specificity. Because of this P. systematic investigation of the various cellular constituents of C.dijhtherk with the object of isolating the type-specific substance was undertaken. On the other hand, it seems also of interest to compare the immunological activities of the various cellular substances. The organism employed for the present study was the well-known Park 8 strain which belongs to Type D41 of Sia and Huang's serological types3 Immune serum was prepared by the intravenous injection of rabbits with well-washed cultures grown on serum-broth, pH 7.6, in accordance with the technic previously This will be referred to as the homologous immune serum. Immune sera were also prepared with other serological types of Sia and Huang's such as D25, D30, D4-0'6287, 12190, and 2 untyped avirulent strains. This group of immune sera will be designated as heterologous immune sera. Organisms were grown on stomach-digest medium' for a week after which they were collected by centrifugation, washed 4 times with distilled water and then with 4 changes of 95% alcohol.The wet bacteria were then suspended in an ether-alcohol mixture (made by mixing equal volumes of each) in the proportion of 20 to 1 respectively contained in a tightly corked flask. The whole mixture was left in the incubator at 37°C for 5 days with frequent agitation lDurmd, P., and Guerin, J., Contpt. rend. SOC. de biol., 1921, M, 980. 2 Eagleton, A. P., and Baxter, E. M., J . Hyg., 1923, Z2, 107. asia, R. €1. P., and Huang, C. H., PRQC. SOC.
