310 THE STREPTOCOCCUS-FNEVMOCOCCVS GROUP 
than they would normally. The injection of sera of actively immun- 
ized animals appears to increase the resistance of non-immunized 
animals to otherwise fatal amounts of streptococci. 
Marmorek/ Tavel- and others have prepared antistreptococcic 
immune sera on a large scale by immunizing horses first with killed 
cultures, then with increasing amounts of living cultures. Marmorek, 
a staunch supporter of the "Einheit" theory that all streptococci 
were identical, used a single strain of organism, whose virulence was 
greatly increased for rabbits prior to injection into horses. Immun- 
ization requires several months. He found that for some days follow- 
ing each injection the horse exhibited a febrile reaction, and during 
that period the serum was toxic for rabbits; streptococci may be found 
in the blood stream during this period. After the temperature has 
reached normal— three weeks or more after the injection— the toxic 
properties disappear and the serum exhibits protective powers when it 
is introduced into rabbits with a lethal dose of streptococci. This 
serum has been used extensively in the treatment of erysipelas, puer- 
peral fever and scarlet fever, but its curative value is still a matter of 
discussion. 
Tavel's serum is essentially like that of Marmorek, except that a 
polyvalent vaccine is used for immunization. Besredka also uses a 
polyvalent vaccine for immunizing horses, but the organisms are 
not exalted in virulence for rabbits by passage through a series of 
them before inoculating horses. Besredka believes that passage 
through rabbits may modify the virulence of the streptococci for 
man, from whom the organisms are obtained for immunizing the 
horses, and for whom the serum is to be used. Streptococcal sera are 
as yet of debatable value; in localized lesions they have frequently 
exhibited some therapeutic value; in the severe generalized infections 
in man they are usually either irregular in their action or inactive. 
Somewhat more encouraging results have been reported where the 
specific immune serum is used in connection with autogenous vaccines 
of streptococci. 
Antibodies.— Aggiut'imns are present in the sera of animals immu- 
nized with streptococcus vaccines, and the degree of agglutinating 
power may be very considerable for homologous strains. The results 
are usually less definite with heterologous strains/ and agglutinins 
developed during immunization with streptococci are of no consider- 
able value in prognosis. The part they may play in immunization 
is problematical. 
Complement-fixation has not been found a satisfactory method for 
identifying streptococci; the results are occasionally variable without 
apparent cause.^ The reaction of anaphylaxis has also been of doubt- 
ful value as a general diagnostic procedure.'^ 
1 Ann. Inst. Pasteur, 1895, 9, 593. - Loc. cit. 
3 Kinsella and Swift: Jour. Exp. Med., 1917, 25, 877. 
" Howell: Jour. Infec. Dis., 1918, 22, 230. 
s Davis: Jour. Infec. Dis., 1913, 12, 3S6. 
