150 
PRINCIPLES OF BACTERIOLOGY 
tions on some sugars, it is not surprising to learn that 
the agglutinins produced by the blood in response to 
these bacteria are also evidently related to each other; 
that is to say, agglutinins caused by injection of typhoid 
bacilli will agglutinate, not only typhoid bacilli, but also 
those of the paratyphoid and colon bacilli although to a 
much lesser extent; those produced by the injection of 
the colon bacillus will cause agglutination—to a much 
lesser degree—of the typhoid and paratyphoid bacilli, etc. 
The expression “to a much lesser degree” means in a 
higher concentration; i. e., in lower dilution; for ex¬ 
ample, the agglutinins caused by injection of the typhoid 
bacilli will agglutinate the typhoid bacilli in the dilu¬ 
tion of the blood serum in salt solution of 1:10,000, while 
they will only agglutinate the colon and the paratyphoid 
bacilli in dilution of 1:200, etc. 
When the injection of an animal with one bacterium 
results in the production of agglutinins not only for that 
organism but also to a lesser extent for other bacteria, 
closely related to it (as when the blood serum of a 
rabbit injected with the typhoid will agglutinate 
not only the typhoid bacilli but also, to a lesser 
degree, i. e., in lower dilutions, the paratyphoid 
and colon bacilli)—such agglutinins clump or ag¬ 
glutinate the entire group, although to a varying 
extent. The specific agglutinins (that is, those 
against the bacteria injected) are called “ major” 
agglutinins and those against other members of the 
groups are called “minor” agglutinins; thus, if a rab¬ 
bit is injected with typhoid bacilli, he will produce the 
major or typhoid agglutinins, and minor or paratyphoid 
and colon agglutinins. 
This is shown in the accompanying table, which is 
copied from the actual work done in our laboratories. 
