STREPTOCOCCUS PYOGENES. 497 
by means of a hypodermatic needle, and each c.c. added 
to a tube of broth, in order to produce an adequate 
development of the cocci, which are found in small 
numbers in the bloodvessels. Petruschky is of the 
opinion that the cocci can best be shown in blood by 
animal inoculation. Having withdrawn from the 
patient 10 c.c. of blood by means of a hypodermatic 
syringe, under aseptic precautions, he injects a portion 
of this into the abdominal cavity of a mouse, while the 
other portion is planted in bouillon. Mice thus inocu- 
lated die from septicemia when virulent streptococci 
are present only in very small numbers in the blood. 
If a successful inoculation takes place we can, through 
the absence or presence of the development of capsules, 
often differentiate between the pneumococcus and the 
streptococcus, which cultures may fail to do. The 
morphological and cultural characteristics of the strep- 
tococcus give us, unfortunately, no absolute knowledge 
as to the influence which the protecting serum will 
-have. The actual test is here our only method. The 
detection of the streptococcus in the blood is in itself 
an unfavorable prognostic sign. 
The blood cultures in perhaps the majority of cases 
of septicemia give no positive results, for many of 
these cases develop their symptoms and even die from 
the absorption of toxins from the local infection, such 
as an amputation wound or an infected uterus or peri- 
toneum, and the bacteria never invade the blood. When 
we get negative results we are, as a rule, utterly unable 
to test the case with curative serums with any accuracy, 
for the sepsis may be due to either the streptococcus, 
colon bacillus, staphylococcus, or a number of other 
pathogenic varieties of bacteria. 
32 
