488 BACTERIOLOGY. 
doses of a streptococcus, which though but slightly 
virulent for them was intensely so for rabbits. 
In none of the streptococcus inflammations do we 
notice much apparent tendency to the production of 
immunizing and curative substances in the blood by a 
single infection. 
Severe general infections dauaily progress to a fatal 
termination after a few days, weeks, or months. It is 
true, however, that cases of erysipelas, cellulitis, and 
abscess, after periods varying from a few days to 
months, tend to recover, and to a certain extent, there- 
fore, we may assume protective processes have been 
called forth. In these cases, however, we know from 
experience that faulty treatment, by lessening the local 
or general resistance, would, as a rule, cause the sub- 
siding infection to again progress and that to perhaps a 
more serious extent than the original attack. Koch 
and Petruschky tried a most interesting experiment. 
They inoculated cutaneously a man suffering from a 
malignant tumor with a streptococcus obtained from 
erysipelas. He developed a moderately severe attack, 
which lasted about ten days. On its subsidence they 
reinoculated him; a new attack developed, which ran 
the same course and over the same area. This was 
repeated ten times with the same results. 
This experiment proved that in this case, at least, 
little if any lasting curative or immunizing substances 
were produced by repeated attacks of erysipelas, and 
that the recovery from each attack was due to local 
and transitory protective developments. 
The severe forms of infection, such as septicemia 
following injuries, operations, and puerperal infections, 
show little tendency to be arrested after being well 
