PATHOGENICITY FOR EXPERIMENTAL ANIMALS 195 



With strains of both Types I and II introduced into a terminal 

 bronchus by means of a catheter, Terrell, Robertson, and Cogge- 

 shall (1933) 1387 made fluoroscopic studies of the lobar pneumonic 

 process which ensued in every instance when appropriate doses of 

 culture were administered. In the experiments of the last-named 

 authors the course of the pneumonia was short, averaging four or 

 five days, while recovery, which took place in the majority of the 

 animals so infected, was abrupt and simulated the crisis occurring 

 in man. Similar experiments with pneumococci of Types I and III 

 Mere described in 1934 by Lieberman and Leopold. 813 The article 

 by Terrell, Robertson, and Coggeshall 1387 contains excellent de- 

 scriptions of the pathological processes observed following intra- 

 bronchial injection of pneumococci in dogs. 



Bull (1916) 173 injected dogs intravenously with pneumococci. 

 Invasion of the blood stream appeared twenty-four to forty-eight 

 hours after the injection. The septicemia reached a climax in 

 four to five days, then abruptly declined, the blood becoming sterile 

 in one to three days after the peak of the septicemia was reached. 

 In some of the animals so injected meningitis occurred. 



The results of a study of meningeal inoculation in dogs have 

 been described by Stewart. 1323 The injection of Type I and Type 

 II organisms into the ventricle, the cistern, and the lumbar region 

 was followed by purulent meningitis with accompanying bacteri- 

 emia when the cultures used were of high virulence. Not all the ani- 

 mals infected succumbed, but those that died showed pathological 

 changes not entirely comparable to those found in pneumococcal 

 meningitis in man. 



THE HORSE 



The susceptibility of horses to infection with Pneumococcus, 

 mentioned by Neufeld and Schnitzer, is a fact all too familiar to 

 those engaged in the manufacture of therapeutic antipneumo- 

 coccic serum. The possession of a high degree of specific, active 

 immunity to pneumococci of a given serological type may fail to 



