PREPARATION OF BACTERIAL ANTIGENS 15 



The periodic titration of an antigen so preserved is displayed 

 in Table IV. 



As shown above, the antigen unit when first tested was 

 .015 c.c. while 2.5 c.c. displayed no anticomplementary effect. 

 After six months, the antigenic unit was .02 c.c. whereas 2.5 c.c. 

 still was not anticomplementary. After one year, the values 

 were the same as at six months. At two years, the antigenic 

 unit was found to be .025 c.c. and 2.5 c.c. displayed a slight 

 anticomplementary action. At three years, the findings were 

 the same as at two, except that the anticomplementary action 

 was slightly increased. Throughout the whole period however, 

 the antigenic value decreased less than one half and the final 

 anticomplementary-antigenic [Ac.-Ag.] index was 60, thus 

 affording an entirely satisfactory antigen for complement 

 fixation reactions. 



CONCLUSIONS 



As stated at the beginning of this paper, the work has been 

 directed to the elimination of certain factors tending to lessen 

 the accuracy of bacterial identification by the antigen-anti- 

 body reaction. 



I conclude that the methods as given above are efficient: 



1. In eliminating complicating non-essential proteins de- 

 rived from the culture medium. 



2. In obtaining from the bacterial cell an increased amount 

 of its essential antigenic proteins with a minimal modification 

 of their chemical structure. 



3. In preserving antigens without desiccation and without 

 the addition of chemical reagents. 



BIBLIOGRAPHY 



1. Jour, of Inf. Dis., Aug., 1916, xix, 2 and 253. 



2. Jour, of Inf. Dis., Feb., 1917, xx, 150. 



3. Annales de 1'Inst. Pasteur, Paris, 1901, 289. 



4. Berl. klin. Wchnschr., 1906, xxxviii, 1243. 



5. Med. Klinik., 1905, Iv. 



6. Centralbl. f. Bakt, 1906, xli. 



7. Berl. klin. Wchnschr., 1907, i. 



8. Berl. klin. Wchnschr., 1907, iii, 68 and 107. 



9. Kolle u. Wassermann, 1913, i, 708. 



10. Jour, of Immunology, 1918, iii, 277. 



11. Jour, of Immunology, 1918, iii, 247. 



