192 BIOLOGY OF PNEUMOCOCCUS 



strains of the organism isolated from the sick monkeys were pneu- 

 mococci of Group IV. At that time, the authors 126 " 7 demonstrated 

 that lobar pneumonia could be consistently produced in members 

 of this animal species (Macacus syrichtus and Cebus capucinus) 

 by the intratracheal injection of minute amounts of culture of a 

 virulent Type I strain. When large quantities of culture were in- 

 troduced into the nose or throat, no lobar pneumonia developed, 

 but the animals became carriers of the inoculated organism and re- 

 mained so for a period of at least a month. 



The susceptibility of the monkey (Macacus rhesus and Cero- 

 pithecus callitrichus) to intracranial or intraspinal inoculation 

 with Pneumococcus was demonstrated in 1912 by Lamar, 775 who 

 described the meningitis following the injections. The experimental 

 disease resembled pneumococcal meningitis in man but ran a more 

 rapid course and was invariably fatal. 



In studying pneumococcal infection and immunity in monkeys, 

 Cecil and Steffen 211 found that Macacus rhesus was most resistant 

 to Type I Pneumococcus and rarely developed true lobar pneu- 

 monia ; Cebus capucinus occupied an intermediate position, occa- 

 sionally showing typical lobar infection but more often interstitial 

 or patchy lesions ; while the Philippine monkey, Macacus syrich- 

 tus, was the most susceptible and was preferable for inoculation 

 experiments because animals of that species develop true lobar 

 pneumonia. 



The existence of the carrier state in normal stock monkeys was 

 also shown by School and Sellards, 1246 who recovered an avirulent 

 strain of Pneumococcus from the Philippine monkey, Pithecus 

 philippinensis. The authors also succeeded in inducing pneumonia 

 in the animals by intratracheal inoculation with a small dose of a 

 broth culture of Type I Pneumococcus that was highly virulent 

 for mice. 



Blake and Cecil, 126 using strains of Type I, II, III, and Group 

 IV pneumococci, by intravenous injection failed to produce pneu- 

 monia in monkeys of the Macacus syrichtus species but reported 



