STREPTOCOCCUS PYOGENES. 487 
Production of Toxic Substances. There is no doubt 
that this micrococcus causes fever, general symptoms 
of intoxication, and death by means of toxic substances 
which it forms in its growth; but what these substances 
are—whether they are due to splitting up of animal 
proteids, or are secretion-products, or whether they are 
contained in the cell-bodies of the organism—what 
their composition is and how they are produced in cul- 
tures we do not know. . 
Susceptibility to Streptococcus Infection. As with the 
other ever-present pus cocci, the staphylococci, which 
have, as a rule, only slight virulence, the streptococcus 
is more likely to invade the tissues, forming abscesses 
or erysipelatous and phlegmonous inflammation in man 
when the standard of health is reduced from any cause, 
and especially when by absorption or retention various 
toxic organic products are present in the body in excess. 
Tt is thus that the liability to these local infections, as 
complications or sequel of various specific infectious 
diseases, in the victims of chronic alcoholism, and con- 
stitutional affections in those exposed to septic emana- 
tions from sewers, etc., and probably in many cases 
from the absorption of toxic products formed in the 
alimentary canal as a result of the ingestion of im- 
proper food, or of abnormal fermentative changes in 
the contents of the intestine, or from constipation, are 
to be explained. 
Immunity. Knorr succeeded in producing a moder- 
ate immunity in rabbits against an intensely virulent 
streptococcus by injections of very slightly virulent 
cultures. Pasquale was able to immunize these ani- 
mals partially against septicemia. Marmorek has 
immunized sheep, asses, and horses against very large 
