186 BIOLOGY OF PNEUMOCOCCUS 



fection after the injection directly into the lung of pneumococci 

 cultivated by several animal passages. 



One objection to the use of these animals is their liability to de- 

 velop spontaneous pneumococcal infection, to become carriers, and 

 thus to transmit infection to other laboratory animals. Such an 

 outbreak was reported in 1922 by Gheorgiu, 512 but no mention was 

 made concerning the type to which the infecting organism be- 

 longed. The presence of pneumococci as secondary invaders in an 

 epidemic among guinea pigs and mice caused by B. bronchisepticus 

 was observed by Keegan. 700 Branch 147 in 1927 reported the pres- 

 ence of pneumococci of Group IV in all of thirty-six guinea pigs in 

 a laboratory epidemic. The organism failed to agglutinate with 

 specific immune serum for the first three fixed types, but by its pro- 

 tein fraction appeared to be related serologically to strains of 

 pneumococci of human origin. The infection took the form of 

 otitis, enlargement of the spleen, lobular and even true lobar pneu- 

 monia. According to Bruckner and Galasesco as well as to Chevrel 

 and Ranque,* spontaneous epidemics sometimes begin with septic 

 abortion of the guinea pigs. 



The presence of pneumococci in the nares of apparently normal 

 guinea pigs and of guinea pigs affected with snuffles, and the oc- 

 currence of natural epidemics of pneumococcal infection in ani- 

 mals of this species, was investigated by Neufeld and Etinger- 

 Tulczynska 984 " 5 in 1931. The organisms responsible for natural 

 infections, including those found in a previous investigation of an 

 outbreak in another colony of animals, when tested by means of 

 the Quellung phenomenon, proved to belong to Type XIX. The 

 strain was only slightly virulent for mice and guinea pigs. The 

 authors found further that animals surviving the intranasal im- 

 plantation of pneumococci of Types I and XIX, as a rule, become 

 carriers of the respective strains. 



Neufeld and Etinger-Tulczynska also noted wide variations in 

 the susceptibility of the animals to natural infection from pneumo- 



* Quoted by Neufeld and Sehnitzer. 



