140 ANAPHYLAXIS, ALLERGY OR HYPERSENSITIVENESS 
digestion. When a protein is injected parenterally into an animal, 
the body cells of the animal elaborate an enzyme which will specifically 
disintegrate it. Among the products of disintegration is the posion- 
ous nucleus or archon in a more or less free state. The liberation of 
this substance causes acute poisoning of the host. This substance, 
for which no antibody or antitoxin has been prepared so far, resembles 
in many respects the "endotoxin" of bacteria. It is, however, inac- 
tivated by boiling with dilute hydrochloric acid for several hours. ^ 
Many of the phenomena of anaphylaxis are readily explained in 
the light of Vaughan's work. The latent period, or preanaphylactic 
state, which intervenes between the injection of a protein and the 
appearance of sensitization is the time required to mature the specific 
enzyme. The specificity of the enzyme (called forth by the stimulus 
of alien protein in the tissues) is determined by the arrangement and 
number of groups arrayed around the poison group of the protein; 
herein lies the specificity of the reaction. The similarity or identity of 
the symptoms of anaphylaxis irrespective of the protein depends upon 
the liberation of the poisonous nucleus (common to all proteins) in a 
relatively free state. The induction of passive sensitization depends 
upon the injection of this specific enzyme, which is present in the 
serum of a sensitized animal, into a non-sensitized animal.- 
Vaughan regards the formation of a specific proteolytic enzyme in 
response to the injection of alien protein into the tissues as a protective 
mechanism to rid the body of foreign substance; the theoretical 
importance of this conception as a purposeful reaction is clearly 
shown in the response of the tissues of the body to bacterial in^'ections. 
The incubation period of many bacterial infections is about two weeks, 
during which clinical symptoms are not pronounced. This is inter- 
preted as the time required by the cells of a host to mature a specific 
enzyme capable of disintegrating the alien protein (bacterial cells). 
The symptomatology of bacterial disease is caused largely by the 
liberation of the poisonous nucleus of the bacterial protein in varying 
amounts in special tissues or organs. Natural immunity to bacterial 
disease, according to this theory, is due to the inability of the organism 
to grow in the tissues of the host; active immunity is conferred on the 
host by the presence of a persistent enzyme which will flisintegrate 
the specific organism whenever it is reintroduced into the body and 
before it has time to develop. In this respect the anaphylactic enzyme 
resembles, or possibly is identical with, a specific bacteriolysin. 
Chemically, the poison nucleus or endotoxin is stated by Vaughan 
to resemble beta-imidazolethylamine, described previously.^ The 
specificity of the anaphylactic reaction depends upon the cleavage 
of the protein molecule by a specific proteolytic enzyme with the 
1 Koessler and Hanke: Jour. Biol. Chem., 1919, 39, 521. 
- The importance of the degradation of protein in the alimentary tract can be appre- 
ciated in the light of what has been stated about anaphylaxis. 
3 See page 7.3. 
