374 THE AMERICAN MONTHLY [Nov. 



After sowing the agar tubes they were kept in the in- 

 cubator for several days at a temperature of 37" C. 

 According to this method ninety-two eyes were exam- 

 ined, one tube culture being made from each eye. Of 

 these ninety-two tubes, fifty-three showed one or more 

 colonies of bacteria, while the rest of the tubes (thirty- 

 nine) were sterile. By this I do not mean to imply that 

 the conjunctivae of the thirty-nine eyes were sterile, but 

 only that such small portion of the secretion as was re- 

 moved by the platinum loop was sterile. In the fifty- 

 three tubes containing bacteria, some eight or ten differ- 

 ent kinds of bacteria were found. In twenty-two cases 

 the staphylococcus epidermidis albus was present; in five 

 pyogenes citreus; in one case pyogenes aureus; in one 

 case the bacillus subtilis; in eight cases a large bacillus 

 growing with small delicate translucent colonies on agar, 

 kind not identified; in one case streptococcus pyogenes. 

 The sources from which these bacteria infected the con- 

 junctivae may perhaps be named as follows in the order 

 of importance: 



1st. The edges of the lids and the mouths of the Mei- 

 bomian glands. 



2d. Unclean hands. 



3d. The air. 



4th. Infected nasal fossae. 



In the case of the normal conjunctiva the last is prob- 

 ably not an important source of infection, since the cur- 

 rent of secretion is constantly downward into the nose. 

 Bach, after injecting cultures of bacteria into the nasal 

 fossa3, was unable to find that they ever made their way 

 into the conjunctival sac. 



On the many kinds of bacteria (twenty-six species) 

 which have been found in the normal conjunctiva, only 

 three have been proved to be pathogenic to man. These 

 are the staphylococcus pyogenes aureus, the staphylo- 

 coccus albus, and the streptococcus pyogenes. It is 



