148 BACTERIOLOGY OF THE EYE 



conjunctivitis may be caused by infection from a very severe case, 

 and vice versa (Morax, Morax and Petit, Weeks, Hofmann). Some of 

 Morax and Petit's cases showed very slight clinical changes. It is, 

 however, quite exceptional for virulent material of this kind to produce 

 no conjunctivitis when inoculated on the conjunctiva. 



In this connexion L. Miiller's experience must be noted : a cica- 

 tricial conjunctiva often reacts less intensely to the Koch- Weeks 

 bacillus. 



Meyerhof has made the same statement to me in a letter. In winter 

 he found the bacilli in cases with a clinically normal conjunctiva, 

 and when the weather became warmer these developed a typical 

 conjunctivitis. In trachomatous patients who at the moment had 

 no conjunctival catarrh, the condition more often remained as it was. 



Differential Diagnosis. 



The recent identification by Pes of the Koch- Weeks bacillus with the 

 diphtheria group, and particularly the Bacillus xcrosis, requires no 

 refutation, as for anyone acquainted with the two organisms a single 

 glance at the peculiarities of the Koch-Weeks organism is sufficient to 

 show that such an identification is quite erroneous. The peculiarity 

 that the Bacillus xcrosis, belonging to the diphtheria group, has a special 

 predilection for growth in culture with the Koch-Weeks bacillus, is 

 responsible for this mistake, as it was for the inability of the earlier 

 investigators to obtain pure cultures. To-day the two forms can be 

 separated with ease and certainty. In a smear preparation such a 

 confusion is impossible, especially when Gram's stain is used. 



Kruse (' Die Mikroorgaiiismen,' Flugge, 1896, ii. 441) reported 

 that Kartulis had cultivated from the conjunctiva a bacillus of similar 

 morphological characters, but of more profuse and yellow growth. 

 This organism at first liquefied gelatine ; later, however, on stab 

 culture, gave the ' nail ' growth. It also grew on potatoes. Kruse 

 named it Bacillus psciido-conjiinctivitidis. In Kruse's Hygien. Institut 

 Ibrahim and Fuad obtained cultures of two similar organisms from 

 the air ; these they named Bacillus aeris minutissinnts and Bacillus 

 aureus mimrtissimus. All three decolorized with Gram's stain. 



These are quite isolated findings, which have never occurred in the 

 enormous number of examinations which have been made of the 

 secretions in Koch- Weeks conjunctivitis ; they are, therefore, of no 

 practical importance in differential diagnosis. Nor will the Koch- 

 Weeks bacillus be confused with any other organism causing con- 



