GENERAL BACTERIOLOGY 
73 
Of the greatest interest and importance are the side 
chains, such as lysins (bacteriolysins, hemolysins, etc.), 
which are called receptors of the third order; we know 
experimentally that when an animal is injected with 
endotoxin-producing bacteria, e. g., cholera spirilla, its 
blood serum contains bacteriolysins; that means that 
if this animal’s blood serum is mixed with cholera 
spirilla the latter will be destroyed—just what happens 
in the animal’s blood; now, if this animal’s blood serum 
should be heated to 56° C. for thirty minutes, and 
then be mixed with cholera spirilla no such bacterial 
Fig. 13.—The receptor of second order (agglutinins and precipitins). 
a, body cell; b, receptor (immune body or side-chain), consisting of two 
parts; c, anchoring group, d, digesting group; e, bacterial poison. 
destruction will take place; this would seem to indi¬ 
cate that the bacteriolysins must have been destroyed 
by heat; yet, if to this heated blood serum a little nor¬ 
mal blood serum from another animal is added, prompt 
destruction of bacteria will take place; this means that 
bacteriolysis is produced by the joint action of two sub¬ 
stances : the specific immune body, produced by the animal 
as a result of injection (the antibody or the bacteriolysin) 
which is not destroyed by heating the blood serum up 
to 56° C. for thirty minutes, and a nonspecific sub- 
