THE NOBMAL CONJUNCTIVA 43 



occurs solely from the action of the orbicularis muscle, especially that 

 portion called Horner's muscle. Under these circumstances, organisms 

 which have got in, even if pathogenic, cannot easily settle down, 

 unless, like the Diplobacillus, Koch-Weeks, etc., they have a special 

 affinity for the conjunctiva. Even when there is a special predilection 

 for organisms, such as occurs in the case of the white Staphylococci 

 and Xerosis, which are always working in from the lids, a true 

 growth only occurs to a very limited extent under normal circum- 

 stances, and similarly the development of a high degree of virulence 

 is difficult. The conjunctival mucus is only a moderately favourable 

 medium for growth (Bach). 



It is well known how, by 'antagonism ?1 or by choking, the presence 

 of the normal saprophytes can hinder other organisms from settling 

 down or growing. It is not known whether any such peculiar property 

 occurs with the commonest inhabitants of the conjunctiva, the white 

 Staphylococci and the Bacillus xerosis, to such an extent as to be 

 important in the pathology of the eye. In cultures they flourish 

 alongside the pathogenic organisms without causing them any 

 demonstrable restriction. Eapidly growing pathogenic forms, such as 

 Staph. aureus, Bac. coli, or Pneumobacillus overgrow the Bacillus xerosis, 

 completely cover the medium, and change its reaction, before this 

 latter organism can develop. In the case of the ordinary Staphylo- 

 coccus albus, which alters media far less rapidly or markedly than 

 the aureus, the development of the Diplobacillus, Koch-Weeks bacillus, 

 influenza bacillus, or Gonococcus 2 is not restricted in spite of their 

 susceptibility and need for alkalinity. 



On the contrary, it is not impossible that the conjunctival inhabi- 

 tants assist in determining the deposition and growth of many germs. 

 The extremely intimate mixture in which xerose and Koch- Weeks 

 bacilli occur in secretions and cultures was long the cause of our 

 inability to obtain pure cultures of the latter, and still makes its pure 

 cultivation exceedingly difficult. In slight cases, where the organism 

 has no high degree of virulence, a mixed growth of xerose and Koch- 

 Weeks bacilli can be cultivated, although the latter often cannot be 

 propagated alone, and dies out. The function of the xerose is 



1 Garre found an antagonist to the Staph. aureus in the Bac. ftuoresc. putridus ; 

 Doderlein, Menge, and Kroenig in the anaerobic vaginal bacilli. 



2 The conclusion which Kandolph (Bull, of Johns Hopkins Hosp., Bait., October, 1906) 

 drew from typhoid bacilli not occurring in the conjunctiva in typhoid fever, and the 

 Pneumococcus being as common there in healthy subjects as in pneumonia patients that 

 these organisms are held off by ' antagonism ' is certainly not proven, and is unlikely. 

 Such an antagonism does not occur in cultures. There is no reason to presume that in 

 these diseases the organisms are very often earned to the conjunctiva. 



