8 MELICK 



culture (as determined by Wright's method) were suspended 

 in i c.c. of NaCl solution. 



After the withdrawal of 10 c.c. of blood from each animal for 

 normal serum controls, the twelve rabbits were injected at 

 five day intervals. The first and second injections were made 

 subcutaneously, the third and fourth intraperitoneally and the 

 fifth, sixth, and seventh intravenously. For test purposes 

 10 c.c. of blood was drawn six days after the last injection and 

 at successive monthly intervals, and in each instance the serum 

 so obtained was titrated for its agglutinating value on the day 

 following the bleeding. 



These determinations showed that the serum from the 

 rabbits which were injected with the organisms grown in the 

 protein-free medium contained as much specific antibody as 

 did the serum from the animals which received organisms 

 grown on the protein-containing medium, even when titrated 

 against organisms grown on the latter medium. The first 

 graph (Table I) displays the curves representing the average 

 titer of each of the two groups of animals at different points. 



From this graph it can be seen that at no time was there 

 a distinct contrast in antibody content in the sera of the two 

 groups of animals. 



A detailed presentation of the titer of the several sera at the 

 time of maximum observed antibody content (six days follow- 

 ing last injection) is given in Table II where the results are 

 shown for each serum as tested with the homologous organism 

 grown in both types of culture medium. 



From the results found in Table II it is apparent that with 

 the groups of organisms under consideration, not only can 

 they be cultivated satisfactorily in the absence of admixed 

 proteins, but that when so cultivated they display the same 

 bacterial antigenic values which the organisms possess when 

 grown in protein-containing media. 



II. The disintegration of bacterial cells with a minimal 

 chemical modification and a maximal liberation of their anti- 

 genic proteins. While the simple saline suspensions of bac- 

 teria as used by Bordet and Gengou 3 in their original work 



