ANTIANAPHYLAXIS 145 
hour. If no symptoms develop, the full dose may be given without 
danger; it is generally believed that even if mild symptoms do follow 
the initial injection, the full dose may be given with safety after one- 
half hour. The first injection appears to abort what otherwise might be 
a reaction dangerous to the patient. This procedure has its counter- 
part in sensitized animals which receive a sublethal injection of pro- 
tein. It is found that under these conditions the animal is no longer 
reactive, and this period of desensitization or anti-anaphylaxis persists 
for several days or weeks. The explanation advanced to account for 
this refractory condition is that the small amount of protein injected 
exliausts, temporarily at least, the anaphylactin. Besredka^ has 
studied this phenomenon of desensitization carefully, and the pro- 
cedure outlined by him is usually followed in clinical practice. 
The present method of concentrating diphtheria antitoxin, and other 
antitoxins as well, by fractional precipitation of the globulin^ appears to 
reduce the incidence of serum sickness very materially. According to 
German investigators, antitoxin which has stood for one or two months 
has lost to a very considerable extent the substance or substances which 
cause the symptoms of serum sickness. 
Practical and Theoretical Considerations. — .4 . Advantage is taken of 
the sensitization of individuals by bacterial protein during certain 
bacterial infections, particularly those with the tubercle bacillus, B. 
mallei, in syphilis, and in general infections that become chronic, for 
diagnostic purposes. It has been shown almost beyond doubt that 
individuals suffering from these diseases are sensitized to the bacterial 
protein, and it is possible to make a fairly definite clinical diagnosis by 
introducing extracts of the specific organisms into the skin and inducing 
there an anaphylactic reaction which, if the dose is small, is local in 
character, but which may be general and severe if the dose is increased 
in amount. The \'on Pirquet, Calmette, Moro and Koch methods of 
utilizing tubercuhn for diagnostic purposes are directly dependent 
upon this reaction of hypersensitiveness. The diagnostic use of mallein 
and luetin depend upon the same phenomenon. 
B. Advantage is also taken of the specificity of the anaphylactic 
reaction for the recognition of proteins. Wells and Osborn^ and many 
others have sensitized guinea-pigs with proteins and then injected 
into these sensitized animals proteins which are to be identified either 
specifically or phylogenetically. The nature and extent of the ana- 
phylactic reaction in these animals furnishes the most delicate test 
(except possibly the precipitin test) which is available for such investi- 
gations. 
1 Ami. Inst. Pasteur, 1910, 24, 879. 
2 Banzhaf: Johns Hopkins Hosp. Bull., 1911, 22, 106. 
' Loc. cit. 
10 
