344 



BACTERIA PATHOGENIC TO MAN 



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, therefore, we may 

 assume that protective agents have been produced. In these cases, how- 

 ever, we know from experience that faulty treatment, by lessening the 

 local or general resistance, would, as a rule, cause the subsiding infection 

 to again progress perhaps even to 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 re- 

 inoculated 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, shoAv little tendency to be arrested 

 after being well established. Having, then, in remembrance, the above 

 facts, let us consider the results already obtained in the experimental 

 immunization and treatment of animals and men suffering from or in 

 danger of infection with streptococci. One method is now chiefly used 

 for the immunization and attempt to produce curative substances in 

 animals, namely the injection in gradually increasing doses of the living, 

 virulent streptococcus itself. Marmorek was the first to attempt the 

 production of a curative serum on a large scale. 



Influence of Serum from Immunized Animals upon Streptococcus Infec- 

 tions in Other Animals. In the table are given the results following the 

 injection of small amounts of a serum which represents in immunizing 

 value what about one-third of the horses are able to produce. In the 

 following experiments the serum and culture were injected subcuta- 

 neously in rabbits at the same time, but in opposite sides of the body : 



TABLE Showing Strength^of Average Grade of Antistreptococcic Serum given by Selected 

 Horses after six months of Injection of suitabe amounts of Living Streptococci. 



