182 BACTEKIOLOGY OF THE EYE 



These positive inoculations are opposed to Axenfeld's results : in 

 eight inoculations with secretion he obtained no reaction, as also in 

 one case in a child. The fact is thus demonstrated that a definite 

 personal variation for susceptibility occurs along with this contagious- 

 ness. The possibility that many secretions may not possess the power 

 of producing an infection in other persons must always be remembered, 

 as was shown by Gifford on his own conjunctiva, which was susceptible 

 to infection, although an inoculation a short time previously with 

 a secretion produced no result. 



This variation in contagiousness is confirmed by the frequent 

 occurrence of isolated sporadic cases, which do not spread in spite 

 of the fact that they have a profuse secretion and abundant oppor- 

 tunity for contact. The exemption of adults in many epidemics is 

 also due to this factor. 



Many people have Pneumococci on their normal conjunctiva. A 

 conjunctivitis, therefore, like a pneumonia, may result from an 

 increase in the virulence of the organisms already present, or from a 

 lowered resistance on the part of the patient. The ' chill ' so often 

 recorded in these cases may in this way have some determining 

 influence. 



We have, therefore, on the one side, the possibility that the disease 

 is the result of a form of self-infection ; on the other, the certainty 

 that the secretion is definitely contagious for the conjunctiva, though 

 not by any means so much so as that from cases of Koch-Weeks, 

 gonococcal, or diplobacillary infections. 



We cannot yet say to what extent a single attack of pneumococcal 

 conjunctivitis will produce immunity. Gifford inoculated himself with 

 a positive result, but after a few weeks was unable to repeat this. In 

 his case, however, an inoculation previous to both of these had had no 

 result, though then he must have been susceptible. A complete proof 

 of immunity would have required a positive result to have been 

 ojbtained in some other individual with the last used inoculation 

 material. Such a test would have been of great interest. 



Findings in the Secretions. 

 PLATE II., FIG. II. 



Pneumococci can, as a rule, be found in enormous numbers during 

 the progress of the disease to its height. They are typical in shape, 

 and occur in pure culture, especially in the small flakes of pus ; they 

 tend to lie in the cells, but are also found free. They differ from those 



