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 usually 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, 

 whi'ch 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 septicaemia 

 following injuries, operations, and puerperal infections, 

 show little tendency to be arrested after being well 



