SPUTUM SEPTICEMIA 395 



2500 c.c. of a virulent culture has been injected into the 

 veins at one time. 



From such highly immunized animals sera have been 

 obtained of remarkable potency in preventing infection; 

 thus Cole found that 0.2 c.c. of serum from one of his 

 immunized horses would protect a mouse from a million- 

 fold the lethal dose of virulent pneumococci, provided the 

 serum and the culture be injected into the animal at the 

 same time. But if the animal be first infected, then the 

 serum has practically no saving powers even though it be 

 injected only a few hours later and in very much larger 

 amounts; in fact, Cole states, it is difficult or impossible 

 to rescue the animal, no matter how much serum is injected. 



We see then that while active immunization is compara- 

 tively easy of accomplishment, the matter is altogether 

 different when the serum of animals so immunized is used 

 for therapeutic purposes. The failure of serum from im- 

 munized animals to assist in the cure of pneumonia or 

 other pnemococcus infection with certainty is variously 

 explained, but as yet none of the explanations are univer- 

 sally accepted. By some it is believed that immune serum 

 has not been used in sufficient quantities; by othess it is 

 believed that if the intensity of the infection exceeds a 

 certain degree that no amount of immune serum will suffice 

 to rescue. This latter view is particularly applicable to 

 pneumonia, a disease in which one is dealing with an unusu- 

 ally severe type of infection associated with enormous 

 numbers of bacteria in the body. 



Cole suggests that the failure of immune serum to exhibit 

 its curative powers in the cure of pneumonia may not be 

 due to too small amounts of serum used, but rather to an 

 inability on the part of the infected body to supply the 



