CONJUNCTIVITIS 123 



Infection of the conjunctiva from without is caused by direct or 

 indirect contact [transference by flies can occur (Welander)], or by 

 air transmission. The last method is comparatively rare. The most 

 important method of air transmission is by spraying. The causal 

 agent, after passing down the nasal duct with the secretion into the 

 nose and mouth, or being already there, is scattered into the air by 

 speaking, coughing, or sneezing. This possibility was first advanced 

 by Lobanow (A.f. 0., 1900, li., p. 431). Eapid and widespread epi- 

 demics may be due to this method. 



The possibility of an air transmission of organisms, either dried or 

 adhering to fine particles of dust, depends on the resisting power to 

 dryness (desiccation) of the organism in question. The literature on 

 this question is collected in the paper by Lobanow already mentioned. 

 The results obtained by Germano and M. Neisser show that, amongst 

 the pathogenic organisms in ophthalmology, the Gonococcus has a 

 very low resistance to drought ; Streptococcus and Pneumococcus resist 

 better, though different stems vary in this respect, the diphtheria 

 organism longer, and Staphylococcus still longer. The spore-forming 

 organisms, amongst which is Subtilis, are the most resistant. Gourfein 

 states that this last organism is transmitted in dust or earth. Some 

 variation occurs in the individual bacteria, according to the method of 

 drying : organisms dried up in secretions retain their vitality longer 

 than when dried in pure culture, as is well known in the case of 

 Pucumococci. We must also differentiate between drying in a very 

 fine desiccation, such as could be wafted about in the air of a room, 

 and drying up of larger particles which could only be moved about by 

 a strong draught. The xerose bacilli, when tested by Lobanow by 

 desiccation in the air of a room, were shown not to be able to resist 

 such drying, and therefore the term Luft-stdbchen so often used is not 

 quite applicable. Further investigation of this subject is required, 

 especially with regard to organisms which produce conjunctivitis. 

 [This has been done in the case of the Diplobacillus by Macnab and 

 Paul.] 



In general, however, air transmission, as a cause of epidemic con- 

 junctivitis, does not play so important a part as does direct or indirect 

 contact. 



Under these circumstances the varying influence of pathogenicity 

 and disposition is a factor of great importance, especially in the case 

 of the facultative producers of conjunctivitis. 



A very interesting example is pneumococcal infection of the conjunctiva, with its 

 peculiar ending, often by a crisis. Many persons have a conjunctiva immune to 



