CONJUNCTIVITIS 125 



that B. subtilis can occasionally cause a conjunctivitis, although in this case we 

 have no analogies from the other mucous membranes. Some original traumatism 

 seems here necessary, such as the introduction of dust or earth. 



The working of disposition is well shown by the fact that the 

 conjunctival affections already mentioned, when occurring in scrofulous 

 patients, can produce the clinical appearances known as ' conjunctivitis 

 phlyctenulosa.' This fact, which will be more fully considered later, 

 is here brought forward because the Diplobacilli often produce and 

 maintain a typical phlyctenular conjunctivitis. The examination of 

 the secretions in such cases is of especial value, as the zinc treatment 

 of the Diplobacilli often terminates the inflammatory condition. In 

 this fact, too, we have an important example of how an affected part 

 may react in characteristically different ways to the same irritant. 



Disposition, too, is concerned with the fact that different forms of 

 conjunctivitis from an epidemiological standpoint are variously dis- 

 tributed over the earth's surface. Although the surrounding con- 

 ditions have much to do with this, still there are many differences 

 which cannot be referred to this factor. In the individual chapters 

 this question of epidemiology will be further discussed. 



It is doubtful whether race has any influence, and certainly there 

 is no proof that such is the case ; only with regard to trachoma is the 

 question urged to any extent. 



The condition of general health has an influence, as we see in the 

 results of ophthalmia neonatorum. 



How far we can allege an inherited specific immunity of the con- 

 junctiva will also be discussed in the special chapters. 



That the conjunctiva partakes in a general immunity is proved in 

 the case of the antitoxic immunity for diphtheria. [We know that an 

 analogous condition occurs in abrin immunity ; there is also a pure 

 local abrin immunity of the conjunctiva (Romer)]. The same may 

 be presumed in the case of pneumococcal immunity, although it is 

 difficult to prove on account of the uncertain action of Pneumococci on 

 the conjunctivas of non-immunized animals. 



Protective bodies for Gonococci can be produced experimentally in 

 animals, but we cannot judge how far a similar state of affairs can 

 occur in the human conjunctiva. 



We cannot even discuss the question with regard to such organisms 

 as Koch-Weeks bacilli or the Diplobacilli, which are exclusively patho- 

 genic for the conjunctiva. 



Persons who are unaffected by the other pathogenic organisms are 

 but slightly indebted to general immunity for their escape ; in those 



