16 
through the intervention of a second body, known A^arionsl}^ as the 
amboceptor, zwichenkorper, immune body, sensitizer, fixative, pre- 
parative, desmon, etc. 
This order of immunity is particularly evident in the 
poisons that have a lytic or dissolving action upon bac- 
teria or the .cells of the body, such as the bacteriolysins, 
hemolysins, and other cytolysins. These poisonous, 
bodies are believed by Buchner to be a ferment, and 
are usually spoken of as the “ complement,” but also as 
the ‘"alexin” (Buchner) or ‘‘cytase” (Metchnikofl). 
One of the remarkable facts connected with the phe- 
nomena of the lytic poisons is that the poison itself, 
fjg. u;.— Thesec- ^^gi^allv Called the Complement, is normallv present in 
ond order of rmmu- ^ 
nity, showing the the blood. The Complement has less resistance to heat 
complement and the intermediary bodv, and is therefore spoken of 
immune body. . , . 
as being thermolabile. 
According to Ehrlich’s theoiw, immunity can 011I3" be obtained 
against the intermediaiy body, which is believed to be specific. This 
intermediaiy body has a greater resistance to heat than the comple- 
ment; that is, it is relatively thermostabile. 
Ehrlich compares the intermediary bod}^ witli diazo-benzaldehyde, 
which bv means of its diazo group is capable of combining with a 
series of bodies, such as aromatic amins,. phenols, keto-methjT bodies, 
etc. , while by means of its aldehyde group it may 
combine with a different series, such as the hy- 
drazins, ammonia radicals, and h3^droc3^anic acid. 
Phenol and h3Tlroc3^anic acid will not directly 
combine, but with diazo-benzaldeh3^de acting as 
an intermediarv bodv, these two substances can 
be brought into combination. Pushing this com- 
parison further, we ma3" say that the aromatic 
])od3% or the phenol, represents a constituent of 
the b#od corpuscle. The diazo-benzaldeh3Tle is 
the intermediaiy bod3", while the poisonous hy- 
drocyanic acid constitutes the complement.^'' 
Welch* veiy ingeniousW extended Ehrlich’s 
conception of immunity to the bacterial cell. 
According to Welch’s views the bacterial cell has the same power of 
defensive action against the poisons produced b3" the cells of higher 
animals that they have against the toxic products of the bacteria. 
« Vaughan and Novy: Cellular toxins, 1902, p. 131. 
^ Welch, William H.: The Huxley lecture on recent studies of immunity with 
special reference to their bearing on pathology. Bull. Johns Hopkins Hosp., Balto.? 
V. 13, (141), Dec., 1902, pp. 285-299. 
Fig. It . — The third order of 
immunity, showing an im- 
mune body having two 
aflBnities. 
