184 BIOLOGY OF PNEUMOCOCCUS 



infection with Pneumococcus is the eye. Tchistovitch (1890), 1381 

 on introducing the organism into the anterior chamber, found that 

 the aqueous humor, instead of being antagonistic to the cocci, 

 served as a medium for their development. According to Neufeld 

 and Schnitzer, injection of virulent strains of pneumococci under 

 the conjunctiva or cornea leads to a severe infection of the eye, 

 which is followed by systemic infection. The same result attended 

 a similar injection of mouse blood containing pneumococci (Gins- 

 berg and Kaufmann, 1913 517 ). 



Chilling and wetting, age, breed, weight, and diet as factors in- 

 fluencing susceptibility. The great variability in the behavior of 

 rabbits toward pneumococcal infection, whether naturally or arti- 

 ficially acquired, may be due to either or both internal or external 

 conditions. Among external causes Kline and Winternitz (1915) 728 

 studied the influence of cold, alcohol, ether, and bromine on rab- 

 bits infected intrabronchially with Pneumococcus. The agents ap- 

 peared to predispose the animal to the development of bronchitis 

 and even bronchopneumonia, but the results were not conclusive. 

 In experiments in which rabbits were given intrabronchial inocula- 

 tions of virulent pneumococci, Stuppy and Falk 1352 found that wet- 

 ting and chilling the animals failed to lower resistance to invasion 

 of the injected pneumococci, but exposure to cold appeared to ren- 

 der the test animals more susceptible to spontaneous infection. 



Freund 484 observed the difference between the reactions of young 

 and adult rabbits to intradermal inoculation with virulent pneu- 

 mococci — confirming the susceptibility of immature individuals 

 earlier reported by Kruse and Pansini. 763 In adult rabbits injected 

 with virulent pneumococci extensive inflammation developed at the 

 site of infection, but bacteriemia and death occurred in relatively 

 few of the animals. Younger animals failed to develop such an ex- 

 tensive inflammatory process and succumbed to bacteriemia. The 

 ability to respond to inoculation with an energetic, local reaction 

 constitutes a barrier which apparently develops with growth of the 

 animal. 



